-
1 ventricular arrhythmia
Медицина: желудочковая аритмия, желудочковая экстрасистолияУниверсальный англо-русский словарь > ventricular arrhythmia
-
2 ventricular arrhythmia
мед.фраз. желудочковая экстрасистолия* * * -
3 VA
1) Общая лексика: острота зрени2) Компьютерная техника: View Attributes, vertical alignment3) Американизм: The Veteran's Administration, Virtual Airline4) Спорт: Virtual Arcade5) Военный термин: Vice Admiral, Volunteer Army, visual aid, vital area, vulnerable area, штурмовая эскадрилья, Veterans Administration (now DVA)6) Техника: vibroacoustics, voltammeter, volt-ammeter, voucher attached, value add time7) Шутливое выражение: Various Anime, Vindictive Amazons8) Химия: Volume Analyzer9) Метеорология: Volcanic Ash10) Юридический термин: Department of Veterans Affairs, Verbal Abuse, Verbal Abuser11) Грубое выражение: Virgin Alarm12) Оптика: voltampere13) Сокращение: Veterans Administration (USA), Veterans Administration, Vicar Apostolic, Vice-Admiral, Video Amplifier, Virginia (US state), Virginia, value, volt-ampere (electrical power), volt-ampere, voltammeter, Holy See (Vatican City State), (Order of) Victoria and Albert, Aircraft speed, Department of Veterans Affairs (US), Fixed Wing, Heavier Than Air Aircraft, Attack (US Navy), Maximum-Design Maneuvering Velocity, Vacation Absence, Vaginal Atrophy, Valor Award (Australian police award), Value Added, Value Analysis, Vanadium, Vanaf (Dutch: From, used in pricing), Varese (Lombardia, Italy), Variable Account, Variable Annuity, Variant Armour (gaming), Variational Approximation, Various Artists, Vatican City State (top level domain), Ve'rification d'Aptitude (Informatique), Vehicle Analysis, Velocity Analysis, Ventanas Alemanas (Guatemala), Ventricular Atrial, Verkaufsagent (German: Selling Agent; Ebay), Vermont American, Inc., Vertex Array (game programming), Vertical Accelerator, Vertical Angle, Veterans Affairs, Veterans Agency (UK government), Vibration Analysis, Vices Agens (Latin: Acting in Place Of, epigraphy), Vickers-Armstrong (British gun manufacturer), Victoria and Albert Order (British), Vietnamese Airlines, View Askew (gaming, Counter Strike), Viral Arthritis, Virtual Address, Virtual Airlines, Virtual Analog, Virtual Assistant, Viscosity Agent (concrete), VisionAIR, Inc (Atlanta, GA public safety software manufacturer), Visual Accounting, Visual Arts, Viterbi Algorithm, Vivaldi, Vixit Annos (Latin: He Lived (insert number) Years, epigraphy), Voice Actor, Voir Aussi (French: See Also), Volcanic Ash (METAR obscuration), Votre Altesse (French: Your Highness), Vulnerability Analyzer (information security)14) Университет: Voice Acting15) Физиология: Vacuum aspiration, Vertebral Artery, Volume Of Alveolar, alveolar capacity, alveolar space volume16) Электроника: Volt Ammeter17) Вычислительная техника: vertically aligned18) Нефть: variable-area19) Кардиология: ventricular arrhythmia (желудочковая аритмия), ventriculoatrial20) Транспорт: Vector For All21) Парфюмерия: винилацетат22) Фирменный знак: Varian, Vayu Air, Virtual Access (Company)23) СМИ: Virtual Acoustic24) Деловая лексика: Vendor Alias25) Полимеры: vinyl acetate26) Программирование: Valid Again, Variable Argument, Variable Arguments, Vector Accumulate27) Автоматика: voltamperemeter28) Пластмассы: Vinyl Asbestos29) Сахалин Ю: value awareness (Approval Team)30) Кабельные производство: вольт-ампер31) Химическое оружие: vulnerability assessment32) Авиационная медицина: visual acuity33) Расширение файла: Visual Age (IBM)34) Нефть и газ: virtual analyzer35) Молекулярная биология: вирус-ассоциированный ( например, о РНК) (virus-associated)36) Должность: Very Artistic37) Единицы измерений: Volt Amperes -
4 Va
1) Общая лексика: острота зрени2) Компьютерная техника: View Attributes, vertical alignment3) Американизм: The Veteran's Administration, Virtual Airline4) Спорт: Virtual Arcade5) Военный термин: Vice Admiral, Volunteer Army, visual aid, vital area, vulnerable area, штурмовая эскадрилья, Veterans Administration (now DVA)6) Техника: vibroacoustics, voltammeter, volt-ammeter, voucher attached, value add time7) Шутливое выражение: Various Anime, Vindictive Amazons8) Химия: Volume Analyzer9) Метеорология: Volcanic Ash10) Юридический термин: Department of Veterans Affairs, Verbal Abuse, Verbal Abuser11) Грубое выражение: Virgin Alarm12) Оптика: voltampere13) Сокращение: Veterans Administration (USA), Veterans Administration, Vicar Apostolic, Vice-Admiral, Video Amplifier, Virginia (US state), Virginia, value, volt-ampere (electrical power), volt-ampere, voltammeter, Holy See (Vatican City State), (Order of) Victoria and Albert, Aircraft speed, Department of Veterans Affairs (US), Fixed Wing, Heavier Than Air Aircraft, Attack (US Navy), Maximum-Design Maneuvering Velocity, Vacation Absence, Vaginal Atrophy, Valor Award (Australian police award), Value Added, Value Analysis, Vanadium, Vanaf (Dutch: From, used in pricing), Varese (Lombardia, Italy), Variable Account, Variable Annuity, Variant Armour (gaming), Variational Approximation, Various Artists, Vatican City State (top level domain), Ve'rification d'Aptitude (Informatique), Vehicle Analysis, Velocity Analysis, Ventanas Alemanas (Guatemala), Ventricular Atrial, Verkaufsagent (German: Selling Agent; Ebay), Vermont American, Inc., Vertex Array (game programming), Vertical Accelerator, Vertical Angle, Veterans Affairs, Veterans Agency (UK government), Vibration Analysis, Vices Agens (Latin: Acting in Place Of, epigraphy), Vickers-Armstrong (British gun manufacturer), Victoria and Albert Order (British), Vietnamese Airlines, View Askew (gaming, Counter Strike), Viral Arthritis, Virtual Address, Virtual Airlines, Virtual Analog, Virtual Assistant, Viscosity Agent (concrete), VisionAIR, Inc (Atlanta, GA public safety software manufacturer), Visual Accounting, Visual Arts, Viterbi Algorithm, Vivaldi, Vixit Annos (Latin: He Lived (insert number) Years, epigraphy), Voice Actor, Voir Aussi (French: See Also), Volcanic Ash (METAR obscuration), Votre Altesse (French: Your Highness), Vulnerability Analyzer (information security)14) Университет: Voice Acting15) Физиология: Vacuum aspiration, Vertebral Artery, Volume Of Alveolar, alveolar capacity, alveolar space volume16) Электроника: Volt Ammeter17) Вычислительная техника: vertically aligned18) Нефть: variable-area19) Кардиология: ventricular arrhythmia (желудочковая аритмия), ventriculoatrial20) Транспорт: Vector For All21) Парфюмерия: винилацетат22) Фирменный знак: Varian, Vayu Air, Virtual Access (Company)23) СМИ: Virtual Acoustic24) Деловая лексика: Vendor Alias25) Полимеры: vinyl acetate26) Программирование: Valid Again, Variable Argument, Variable Arguments, Vector Accumulate27) Автоматика: voltamperemeter28) Пластмассы: Vinyl Asbestos29) Сахалин Ю: value awareness (Approval Team)30) Кабельные производство: вольт-ампер31) Химическое оружие: vulnerability assessment32) Авиационная медицина: visual acuity33) Расширение файла: Visual Age (IBM)34) Нефть и газ: virtual analyzer35) Молекулярная биология: вирус-ассоциированный ( например, о РНК) (virus-associated)36) Должность: Very Artistic37) Единицы измерений: Volt Amperes -
5 va
1) Общая лексика: острота зрени2) Компьютерная техника: View Attributes, vertical alignment3) Американизм: The Veteran's Administration, Virtual Airline4) Спорт: Virtual Arcade5) Военный термин: Vice Admiral, Volunteer Army, visual aid, vital area, vulnerable area, штурмовая эскадрилья, Veterans Administration (now DVA)6) Техника: vibroacoustics, voltammeter, volt-ammeter, voucher attached, value add time7) Шутливое выражение: Various Anime, Vindictive Amazons8) Химия: Volume Analyzer9) Метеорология: Volcanic Ash10) Юридический термин: Department of Veterans Affairs, Verbal Abuse, Verbal Abuser11) Грубое выражение: Virgin Alarm12) Оптика: voltampere13) Сокращение: Veterans Administration (USA), Veterans Administration, Vicar Apostolic, Vice-Admiral, Video Amplifier, Virginia (US state), Virginia, value, volt-ampere (electrical power), volt-ampere, voltammeter, Holy See (Vatican City State), (Order of) Victoria and Albert, Aircraft speed, Department of Veterans Affairs (US), Fixed Wing, Heavier Than Air Aircraft, Attack (US Navy), Maximum-Design Maneuvering Velocity, Vacation Absence, Vaginal Atrophy, Valor Award (Australian police award), Value Added, Value Analysis, Vanadium, Vanaf (Dutch: From, used in pricing), Varese (Lombardia, Italy), Variable Account, Variable Annuity, Variant Armour (gaming), Variational Approximation, Various Artists, Vatican City State (top level domain), Ve'rification d'Aptitude (Informatique), Vehicle Analysis, Velocity Analysis, Ventanas Alemanas (Guatemala), Ventricular Atrial, Verkaufsagent (German: Selling Agent; Ebay), Vermont American, Inc., Vertex Array (game programming), Vertical Accelerator, Vertical Angle, Veterans Affairs, Veterans Agency (UK government), Vibration Analysis, Vices Agens (Latin: Acting in Place Of, epigraphy), Vickers-Armstrong (British gun manufacturer), Victoria and Albert Order (British), Vietnamese Airlines, View Askew (gaming, Counter Strike), Viral Arthritis, Virtual Address, Virtual Airlines, Virtual Analog, Virtual Assistant, Viscosity Agent (concrete), VisionAIR, Inc (Atlanta, GA public safety software manufacturer), Visual Accounting, Visual Arts, Viterbi Algorithm, Vivaldi, Vixit Annos (Latin: He Lived (insert number) Years, epigraphy), Voice Actor, Voir Aussi (French: See Also), Volcanic Ash (METAR obscuration), Votre Altesse (French: Your Highness), Vulnerability Analyzer (information security)14) Университет: Voice Acting15) Физиология: Vacuum aspiration, Vertebral Artery, Volume Of Alveolar, alveolar capacity, alveolar space volume16) Электроника: Volt Ammeter17) Вычислительная техника: vertically aligned18) Нефть: variable-area19) Кардиология: ventricular arrhythmia (желудочковая аритмия), ventriculoatrial20) Транспорт: Vector For All21) Парфюмерия: винилацетат22) Фирменный знак: Varian, Vayu Air, Virtual Access (Company)23) СМИ: Virtual Acoustic24) Деловая лексика: Vendor Alias25) Полимеры: vinyl acetate26) Программирование: Valid Again, Variable Argument, Variable Arguments, Vector Accumulate27) Автоматика: voltamperemeter28) Пластмассы: Vinyl Asbestos29) Сахалин Ю: value awareness (Approval Team)30) Кабельные производство: вольт-ампер31) Химическое оружие: vulnerability assessment32) Авиационная медицина: visual acuity33) Расширение файла: Visual Age (IBM)34) Нефть и газ: virtual analyzer35) Молекулярная биология: вирус-ассоциированный ( например, о РНК) (virus-associated)36) Должность: Very Artistic37) Единицы измерений: Volt Amperes -
6 MAT
1) Компьютерная техника: Modular Administration Tool, mean acquisition time2) Американизм: Minimum Alternate Tax3) Военный термин: Medium Assault Transport, Minimum Activity Tour, mechanical aptitude test, military advisory team, military air transport, military aircraft types, mine assembly team, missile acceptance team, missile acceptance tests, missile adapter tester, missile, antitank, mobile aerial target, mobile arming tower, mobile assistance team, multiple address telegram5) Математика: Multi Auto Transformation6) Метеорология: Moist Acidic Tundra7) Юридический термин: Marijuana Action Team8) Автомобильный термин: manifold air temperature9) Биржевой термин: Moving Average Treasury10) Сокращение: Marksman Advanced Trainer, Master of Arts in Teaching, Measurement of Atmosphere Turbulence, Modular Advanced Test, Multi-Arms Trainer, multi-focal atrial tachycardia, M1 Abrams Tank, MAC Address Translation, Machine-Assisted Translation, Maintenance Access Terminal, Maintenance Augmentation Team, Maintenance Tape, Maintenance and Administration Terminal, Major Area Team, Male Annihilation Technique ( fruit flies control), Man About Town, Management Aptitude Test, Management Assistance Team, Management, Administrative, and Technological, Manual Angle Tracking, Map Administration Tool, Maryland Accessible Telecommunications Program, Master Automotive Technician, Masters in the Art of Teaching, Material/Materiel, Material/Mine Assembly Team, Materials Management, Mathematics, Matte, Maximum Attainable Throughput, Mean Annual Temperature, Media Access Time, Medical Analysis Tool, Medical Association of Thailand, Medication Administration Technician, Memory Acceleration Technology, Meridian Administration Tool, Metropolitan Achievement Test, Metropolitan Area Transit, Metropolitan Area Trunks, Michigan Association of Timbermen, Microdyne Automated Terminal, Microscopic Agglutination Test, Military Air Traffic, Miller Analogies Test, Miller Analysis Test, Minimal Aggregate Traffic, Minimum Activity Tour (US Navy), Mission Applications Tool, Mission Area Team, Mixed Air Temperature (HVAC systems), Mobile Access Terminal, Mobile Advisory Team, Mobile Aeronautical Telemetry, Mobile Agent Technology, Mobilization Assistance Team, Modular Alarm Transmitter, Module Acceptance Test, Monitoring, Analysis and Testing, Monthly Average Treasury, Morehead Area Transit (Kentucky, USA), Moscow Art Theater, Moscow Arts Theatre, Movement Area Training, Moving Annual Total, Moving Treasuries Average, Mu Alpha Theta (national high school and junior college mathematics club for honors students), Multi Axis Trainer, Multifocal Atrial Tachycardia (type of supra ventricular arrhythmia), Multiple Access Transponder, Municipal Association of Tasmania, Muscle Activation Technique, Myoskeletal Alignment Techniques11) Физиология: Maternal, Medication Administration Training12) Вычислительная техника: machine-aided translation, microalloy transistor13) Иммунология: microagglutination technique14) Транспорт: Marine Aviation Transport15) Экология: Measurement of Atmospheric Turbulence16) Деловая лексика: Machine Automation Tools, Model Action Talk, Most Appreciated Team17) Программирование: Multiply And Add To18) Автоматика: manufacturing automation technology19) Расширение файла: Micro Alloy Transistor, Table shortcut (MS Access), Matrix data file (Matlab)21) Программное обеспечение: Multimedia Authoring Tool -
7 Mat
1) Компьютерная техника: Modular Administration Tool, mean acquisition time2) Американизм: Minimum Alternate Tax3) Военный термин: Medium Assault Transport, Minimum Activity Tour, mechanical aptitude test, military advisory team, military air transport, military aircraft types, mine assembly team, missile acceptance team, missile acceptance tests, missile adapter tester, missile, antitank, mobile aerial target, mobile arming tower, mobile assistance team, multiple address telegram5) Математика: Multi Auto Transformation6) Метеорология: Moist Acidic Tundra7) Юридический термин: Marijuana Action Team8) Автомобильный термин: manifold air temperature9) Биржевой термин: Moving Average Treasury10) Сокращение: Marksman Advanced Trainer, Master of Arts in Teaching, Measurement of Atmosphere Turbulence, Modular Advanced Test, Multi-Arms Trainer, multi-focal atrial tachycardia, M1 Abrams Tank, MAC Address Translation, Machine-Assisted Translation, Maintenance Access Terminal, Maintenance Augmentation Team, Maintenance Tape, Maintenance and Administration Terminal, Major Area Team, Male Annihilation Technique ( fruit flies control), Man About Town, Management Aptitude Test, Management Assistance Team, Management, Administrative, and Technological, Manual Angle Tracking, Map Administration Tool, Maryland Accessible Telecommunications Program, Master Automotive Technician, Masters in the Art of Teaching, Material/Materiel, Material/Mine Assembly Team, Materials Management, Mathematics, Matte, Maximum Attainable Throughput, Mean Annual Temperature, Media Access Time, Medical Analysis Tool, Medical Association of Thailand, Medication Administration Technician, Memory Acceleration Technology, Meridian Administration Tool, Metropolitan Achievement Test, Metropolitan Area Transit, Metropolitan Area Trunks, Michigan Association of Timbermen, Microdyne Automated Terminal, Microscopic Agglutination Test, Military Air Traffic, Miller Analogies Test, Miller Analysis Test, Minimal Aggregate Traffic, Minimum Activity Tour (US Navy), Mission Applications Tool, Mission Area Team, Mixed Air Temperature (HVAC systems), Mobile Access Terminal, Mobile Advisory Team, Mobile Aeronautical Telemetry, Mobile Agent Technology, Mobilization Assistance Team, Modular Alarm Transmitter, Module Acceptance Test, Monitoring, Analysis and Testing, Monthly Average Treasury, Morehead Area Transit (Kentucky, USA), Moscow Art Theater, Moscow Arts Theatre, Movement Area Training, Moving Annual Total, Moving Treasuries Average, Mu Alpha Theta (national high school and junior college mathematics club for honors students), Multi Axis Trainer, Multifocal Atrial Tachycardia (type of supra ventricular arrhythmia), Multiple Access Transponder, Municipal Association of Tasmania, Muscle Activation Technique, Myoskeletal Alignment Techniques11) Физиология: Maternal, Medication Administration Training12) Вычислительная техника: machine-aided translation, microalloy transistor13) Иммунология: microagglutination technique14) Транспорт: Marine Aviation Transport15) Экология: Measurement of Atmospheric Turbulence16) Деловая лексика: Machine Automation Tools, Model Action Talk, Most Appreciated Team17) Программирование: Multiply And Add To18) Автоматика: manufacturing automation technology19) Расширение файла: Micro Alloy Transistor, Table shortcut (MS Access), Matrix data file (Matlab)21) Программное обеспечение: Multimedia Authoring Tool -
8 mat
1) Компьютерная техника: Modular Administration Tool, mean acquisition time2) Американизм: Minimum Alternate Tax3) Военный термин: Medium Assault Transport, Minimum Activity Tour, mechanical aptitude test, military advisory team, military air transport, military aircraft types, mine assembly team, missile acceptance team, missile acceptance tests, missile adapter tester, missile, antitank, mobile aerial target, mobile arming tower, mobile assistance team, multiple address telegram5) Математика: Multi Auto Transformation6) Метеорология: Moist Acidic Tundra7) Юридический термин: Marijuana Action Team8) Автомобильный термин: manifold air temperature9) Биржевой термин: Moving Average Treasury10) Сокращение: Marksman Advanced Trainer, Master of Arts in Teaching, Measurement of Atmosphere Turbulence, Modular Advanced Test, Multi-Arms Trainer, multi-focal atrial tachycardia, M1 Abrams Tank, MAC Address Translation, Machine-Assisted Translation, Maintenance Access Terminal, Maintenance Augmentation Team, Maintenance Tape, Maintenance and Administration Terminal, Major Area Team, Male Annihilation Technique ( fruit flies control), Man About Town, Management Aptitude Test, Management Assistance Team, Management, Administrative, and Technological, Manual Angle Tracking, Map Administration Tool, Maryland Accessible Telecommunications Program, Master Automotive Technician, Masters in the Art of Teaching, Material/Materiel, Material/Mine Assembly Team, Materials Management, Mathematics, Matte, Maximum Attainable Throughput, Mean Annual Temperature, Media Access Time, Medical Analysis Tool, Medical Association of Thailand, Medication Administration Technician, Memory Acceleration Technology, Meridian Administration Tool, Metropolitan Achievement Test, Metropolitan Area Transit, Metropolitan Area Trunks, Michigan Association of Timbermen, Microdyne Automated Terminal, Microscopic Agglutination Test, Military Air Traffic, Miller Analogies Test, Miller Analysis Test, Minimal Aggregate Traffic, Minimum Activity Tour (US Navy), Mission Applications Tool, Mission Area Team, Mixed Air Temperature (HVAC systems), Mobile Access Terminal, Mobile Advisory Team, Mobile Aeronautical Telemetry, Mobile Agent Technology, Mobilization Assistance Team, Modular Alarm Transmitter, Module Acceptance Test, Monitoring, Analysis and Testing, Monthly Average Treasury, Morehead Area Transit (Kentucky, USA), Moscow Art Theater, Moscow Arts Theatre, Movement Area Training, Moving Annual Total, Moving Treasuries Average, Mu Alpha Theta (national high school and junior college mathematics club for honors students), Multi Axis Trainer, Multifocal Atrial Tachycardia (type of supra ventricular arrhythmia), Multiple Access Transponder, Municipal Association of Tasmania, Muscle Activation Technique, Myoskeletal Alignment Techniques11) Физиология: Maternal, Medication Administration Training12) Вычислительная техника: machine-aided translation, microalloy transistor13) Иммунология: microagglutination technique14) Транспорт: Marine Aviation Transport15) Экология: Measurement of Atmospheric Turbulence16) Деловая лексика: Machine Automation Tools, Model Action Talk, Most Appreciated Team17) Программирование: Multiply And Add To18) Автоматика: manufacturing automation technology19) Расширение файла: Micro Alloy Transistor, Table shortcut (MS Access), Matrix data file (Matlab)21) Программное обеспечение: Multimedia Authoring Tool
См. также в других словарях:
ventricular arrhythmia — an arrhythmia originating in the ventricles … Medical dictionary
Re-entry ventricular arrhythmia — Infobox Disease Name = PAGENAME Caption = DiseasesDB = ICD10 = ICD10|I|47|0|i|30 ICD9 = ICDO = OMIM = MedlinePlus = eMedicineSubj = eMedicineTopic = MeshID = Re entry ventricular arrhythmia is a type of paroxysmal tachycardia where the cause of… … Wikipedia
Ventricular tachycardia — Classification and external resources ICD 10 I … Wikipedia
Ventricular fibrillation — Infobox Disease Name = PAGENAME Caption = ECG lead showing VF DiseasesDB = ICD10 = ICD10|I|49|0|i|40 ICD9 = ICD9|427.41 ICDO = OMIM = MedlinePlus = eMedicineSubj = eMedicineTopic = MeshID = D014693 Ventricular fibrillation (V fib or VF) is a… … Wikipedia
arrhythmia — arrhythmic /euh ridh mik, ay ridh /, arrhythmical, adj. arrhythmically, adv. /euh ridh mee euh, ay ridh /, n. Pathol. any disturbance in the rhythm of the heartbeat. Also, arhythmia. [1885 90; < NL < Gk arrhythmía. See A 6, RHYTHM, IA] * * *… … Universalium
ventricular fibrillation — Pathol. a cardiac arrhythmia characterized by rapid, chaotic electrical impulses to the ventricles, incomplete ventricular contractions, and resultant loss of pulse and blood pressure. * * * Uncoordinated contraction of the muscle fibres of the… … Universalium
ventricular fibrillation — noun fibrillation of heart muscles resulting in interference with rhythmic contractions of the ventricles and possibly leading to cardiac arrest • Hypernyms: ↑fibrillation, ↑cardiac arrhythmia, ↑arrhythmia * * * noun : very rapid uncoordinated… … Useful english dictionary
Arrhythmia — An abnormal heart rhythm. In an arrhythmia the heartbeats may be too slow, too rapid, too irregular, or too early. Rapid arrhythmias (greater than 100 beats per minute) are called tachycardias. Slow arrhythmias (slower than 60 beats per minute)… … Medical dictionary
Ventricular tachycardia — An abnormally rapid heart rhythm that originates from a ventricle, one of the lower chambers of the heart. Although the beat is regular, ventricular tachycardia is life threatening because it can lead to a dreaded condition, ventricular… … Medical dictionary
Ventricular fibrillation — An abnormal irregular heart rhythm whereby there are very rapid uncoordinated fluttering contractions of the lower chambers (ventricles) of the heart. Ventricular fibrillation disrupts the synchrony between the heartbeat and the pulse beat.… … Medical dictionary
arrhythmia — noun an abnormal rate of muscle contractions in the heart • Syn: ↑cardiac arrhythmia • Derivationally related forms: ↑arrhythmic • Hypernyms: ↑heart disease, ↑cardiopathy • Hyponyms … Useful english dictionary