Main definitions of a in English

: a1A2A3a4

a1

(also an)

Pronunciation: /ə//eɪ/

determiner

  • 1Used when mentioning someone or something for the first time in a text or conversation.

    ‘a man came out of the room’
    Compare with the
    ‘it has been an honour to meet you’
    • ‘Children need a place for their computer equipment, and parents need closet space for their clothing.’
    • ‘We had to write a story about a natural disaster for creative writing.’
    • ‘He has also written an opera and translated Dante's Inferno in order to produce an illustrated book of it.’
    • ‘Jack crouched down and hid behind a tree trunk.’
    • ‘Before making a decision, do an assessment of how you want to use your phone.’
    • ‘My wife got me an unexpected Christmas gift this year.’
    • ‘Bob's conducting a three-year internet romance with a girl he's never met.’
    • ‘An internal report written by a manager at the nuclear waste reprocessing plant was leaked this week.’
    • ‘I received an email from Jo today.’
    • ‘"That campaign definitely had an effect," she says.’
    1. 1.1Used with units of measurement to mean one such unit.
      ‘a hundred’
      ‘a quarter of an hour’
      • ‘I look at these miserable people, and wouldn't trade my life with theirs for a million dollars.’
      • ‘I sent off an e-mail, just an hour ago, and he's already got me back online.’
      • ‘I stopped to pick up a gallon of milk on my way home from work.’
      • ‘The attack came amid a major upsurge in violence across the country that has left a thousand dead.’
      • ‘About a mile further down the road, another dog ran out in front of the taxi.’
      • ‘There is barely an ounce of fat on his body, and he continues to make his team-mates look chubby.’
    2. 1.2[with negative]One single; any.
      ‘I simply haven't a thing to wear’
      • ‘Incensed at the fiasco, I went back to the website to try and find a telephone number to call - not a thing!’
      • ‘I had to own up to the fact that I'd never read a word by Crofts.’
      • ‘I think there's not a person born that doesn't have a gift to offer in some way.’
      • ‘The film looks fantastic: there is not a spot, or a scratch, or a visual defect to be seen.’
      • ‘Most refugees say they never saw a drop of food aid - despite almost one million tonnes flooding into the country every year.’
    3. 1.3Used when mentioning the name of someone not known to the speaker.
      ‘a Mr Smith telephoned’
      • ‘On September 29 a letter arrived at our address for a Ms L Doherty.’
      • ‘Does anyone know a Mr Daeller?’
      • ‘She was born in about 1670, the daughter of a Mr Freeman of Holbeach in Lincolnshire.’
      • ‘He was sent two poems from a Miss Ethel Malley, who wrote saying they were found among her brother's possessions after his death.’
      • ‘The latest letter was from a Mrs Singh, who complained about two radio stations.’
    4. 1.4Someone like (the name specified)
      ‘you're no better than a Hitler’
      • ‘You need the methods of a Roosevelt.’
      • ‘Regarding academic medicine, it has become increasingly difficult for a Freud or a Mendel to gain recognition without university affiliation or corporate sponsorship.’
      • ‘Moore says that the organization has passed its Chamberlain period, and is now in need of a Churchill.’
      • ‘What he lacks is the charisma of an Olivier, whose epochal Coriolanus is dazzlingly evoked in two pages of Kenneth Tynan's Curtains.’
      • ‘Called a Judas by his countrymen, he received an elbow from another player, and left the pitch injured.’
  • 2Used to indicate membership of a class of people or things.

    ‘he is a lawyer’
    ‘this car is a BMW’
    • ‘In 1984 he was granted his fervent wish to acquire a Picasso.’
    • ‘She's a banker, married to a stockbroker, and they have a daughter about the same age as Amy.’
    • ‘Notice that every car seen in the show is a Chevrolet, out of consideration for their sponsor.’
    • ‘Lilly is a Siamese cat who survived a two-week cross-country move while stuck in a drawer.’
    • ‘My mom's a pharmacist and my dad's a realtor.’
  • 3In, to, or for each; per (used when expressing rates or ratios)

    ‘typing 60 words a minute’
    ‘a move to raise petrol prices by 3p a litre’
    • ‘You can't drive over five miles an hour down any street in New York.’
    • ‘The site takes in 2,000 tons of trash on a typical day, charging an average $30 a ton.’
    • ‘I type 15 words a minute with a lot of mistakes.’
    • ‘The truckers are angry at the rise in diesel prices, which currently average 81.3p a litre.’
    • ‘The price of gold rose last week to $309 an ounce - and at one point was $312, its highest for two years.’

Usage

On the question of using a or an before words beginning with h, see an

Origin

Middle English: weak form of Old English ān ‘one’.

Pronunciation:

a

/ə//eɪ/

Main definitions of a in English

: a1A2A3a4

A2

(also a)

noun

  • 1The first letter of the alphabet.

    1. 1.1Denoting the first in a set of items, categories, sizes, etc.
    2. 1.2Denoting the first of two or more hypothetical people or things.
      ‘suppose A had killed B’
    3. 1.3The highest class of academic mark.
      ‘a dazzling array of straight A's’
    4. 1.4(in the UK) denoting the most important category of road, other than a motorway.
      ‘the A34’
      ‘busy A-roads’
    5. 1.5Denoting the highest-earning socio-economic category for marketing purposes, including top management and senior professional personnel.
    6. 1.6Chess
      Denoting the first file from the left, as viewed from White's side of the board.
    7. 1.7The first constant to appear in an algebraic expression.
    8. 1.8Geology
      Denoting the uppermost soil horizon, especially the topsoil.
    9. 1.9The human blood type (in the ABO system) containing the A antigen and lacking the B.
    10. 1.10(with numeral) denoting a series of international standard paper sizes each twice the area of the next, as A0, A1, A2, A3, A4, etc., A4 being 210 × 297 mm.
  • 2A shape like that of a capital A.

    [in combination] ‘an A-shape’
  • 3Music
    The sixth note of the diatonic scale of C major. The A above middle C is usually used as the basis for tuning and in modern music has a standard frequency of 440 Hz.

    1. 3.1A key based on a scale with A as its keynote.

Pronunciation:

A

/eɪ/

Main definitions of a in English

: a1A2A3a4

A3

  • 1(in card games) ace.

    ‘you cash ♥AK’
  • 2Against (heading the column in a table of sports results which shows the goals or points scored against each club).

  • 3informal A level.

  • 4Ampere(s).

  • 5Ångstrom(s).

  • 6Attack (in designations of US aircraft types)

    ‘an A-10’
  • 7Answer.

    ‘Q: What is a hung parliament? A: One in which no single party has an overall majority’
  • 8(in names of sports clubs) Athletic.

    ‘Dunfermline A’
  • 9Austria (international vehicle registration).

Main definitions of a in English

: a1A2A3a4

a4

  • 1(in travel timetables) arrives.

    ‘Penzance a 0915’
  • 2[in combination] (in units of measurement) atto- (10−18).

  • 3British (with reference to sporting fixtures) away.

    ‘March 15 Sheffield United (a)’
  • 4(used before a date) before.

    ‘a1200’

Physics
  • Acceleration.