Main definitions of a in US English:

: a1a2A3

a1

(also an)

determiner

  • 1Used when referring to 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 honor to have you’
    ‘we need people with a knowledge of languages’
    • ‘He has also written an opera and translated Dante's Inferno in order to produce an illustrated book of it.’
    • ‘I received an email from Jo today.’
    • ‘My wife got me an unexpected Christmas gift this year.’
    • ‘Children need a place for their computer equipment, and parents need closet space for their clothing.’
    • ‘Jack crouched down and hid behind a tree trunk.’
    • ‘An internal report written by a manager at the nuclear waste reprocessing plant was leaked this week.’
    • ‘"That campaign definitely had an effect," she says.’
    • ‘Before making a decision, do an assessment of how you want to use your phone.’
    • ‘Bob's conducting a three-year internet romance with a girl he's never met.’
    • ‘We had to write a story about a natural disaster for creative writing.’
    1. 1.1 Used with units of measurement to mean one such unit.
      ‘a hundred’
      ‘a quarter of an hour’
      • ‘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.’
      • ‘There is barely an ounce of fat on his body, and he continues to make his team-mates look chubby.’
      • ‘About a mile further down the road, another dog ran out in front of the taxi.’
      • ‘I look at these miserable people, and wouldn't trade my life with theirs for a million dollars.’
      • ‘The attack came amid a major upsurge in violence across the country that has left a thousand dead.’
    2. 1.2with negative One single; any.
      ‘I simply haven't a thing to wear’
      • ‘I had to own up to the fact that I'd never read a word by Crofts.’
      • ‘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.’
      • ‘Incensed at the fiasco, I went back to the website to try and find a telephone number to call - not a thing!’
      • ‘I think there's not a person born that doesn't have a gift to offer in some way.’
    3. 1.3 Used 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.’
      • ‘He was sent two poems from a Miss Ethel Malley, who wrote saying they were found among her brother's possessions after his death.’
      • ‘She was born in about 1670, the daughter of a Mr Freeman of Holbeach in Lincolnshire.’
      • ‘The latest letter was from a Mrs Singh, who complained about two radio stations.’
      • ‘Does anyone know a Mr Daeller?’
    4. 1.4 Someone like (the name specified)
      ‘you're no better than a Hitler’
      • ‘You need the methods of a Roosevelt.’
      • ‘What he lacks is the charisma of an Olivier, whose epochal Coriolanus is dazzlingly evoked in two pages of Kenneth Tynan's Curtains.’
      • ‘Moore says that the organization has passed its Chamberlain period, and is now in need of a Churchill.’
      • ‘Regarding academic medicine, it has become increasingly difficult for a Freud or a Mendel to gain recognition without university affiliation or corporate sponsorship.’
      • ‘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’
    • ‘Notice that every car seen in the show is a Chevrolet, out of consideration for their sponsor.’
    • ‘In 1984 he was granted his fervent wish to acquire a Picasso.’
    • ‘Lilly is a Siamese cat who survived a two-week cross-country move while stuck in a drawer.’
    • ‘She's a banker, married to a stockbroker, and they have a daughter about the same age as Amy.’
    • ‘My mom's a pharmacist and my dad's a realtor.’
  • 3Used when expressing rates or ratios; in, to, or for each; per.

    ‘typing 60 words a minute’
    ‘cost as much as eight dollars a dozen’
    • ‘The truckers are angry at the rise in diesel prices, which currently average 81.3p 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 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

Main definitions of a in US English:

: a1a2A3

a2

  • 1(in travel timetables) arrives.

    ‘Penzance a 0915’
  • 2in 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’

"a"
Physics
  • Acceleration.

Main definitions of a in US English:

: a1a2A3

A3

(also a)

noun

  • 1The first letter of the alphabet.

    1. 1.1 Denoting the first in a set of items, categories, sizes, etc.
    2. 1.2 Denoting the first of two or more hypothetical people or things.
      ‘suppose A had killed B’
    3. 1.3 The highest class of academic mark.
    4. 1.4Chess Denoting the first file from the left, as viewed from White's side of the board.
    5. 1.5 The first fixed quantity in an algebraic expression.
    6. 1.6"A" The human blood type (in the ABO system) containing the A agglutinogen and lacking the B.
  • 2A shape like that of a capital A.

    in combination ‘an A-shape’
    See also A-frame, A-line
  • 3Music
    The sixth note of the diatonic scale of C major.

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

Phrases

  • from A to B

    • From one's starting point to one's destination.

      ‘most road atlases will get you from A to B’
      • ‘As well as finding you the best way from A to B, the operators can also provide an emergency and breakdown service.’
      • ‘Ask the ‘British Bobby’ for the nearest toilet or how to get from A to B, it is all part of his job.’
      • ‘I wanted to show people how to get from A to B in your life.’
      • ‘You could go from A to B directly, walking fast, neglecting the scenery, or instead you could choose to take your time.’
      • ‘People who need to travel from A to B will take an alternative route.’
      • ‘We need to put all the other things to one side and get from A to B safely at the appropriate speed.’
      • ‘It must also be rather boring and predictable sailing directly and single-mindedly from A to B to C.’
      • ‘The drivers are not concentrating and just going from A to B to distribute the goods.’
      • ‘How else would you get someone from A to B unless you've used an airplane?’
      • ‘She said: ‘People will still be able to get from A to B - it may just take them that bit longer.’’
  • from A to Z

    • Over the entire range; completely.

      ‘make sure you understand the subject from A to Z’
      • ‘They could argue about who was smarter, who the teachers liked best, anything from A to Z they could argue about.’
      • ‘The person has to fit from A to Z or else they're just not wanted.’
      • ‘Going through your list of accounts from A to Z won't really work.’
      • ‘Instead, the opposition wants an independent committee to oversee the election from A to Z.’
      • ‘If everything is explained to us, from A to Z, then even an idiot can grasp it.’
      • ‘They moved in with a heavy barrage of speculation from A to Z.’
      • ‘Most of my work has been in the comedy genre, so it's a dream role to get a chance to play a character that has a trajectory from A to Z.’
      • ‘It wouldn't be something I'd have to take from A to Z, point-by-point, and argue and describe.’
      • ‘The process moves from A to Z without cutting corners.’
      • ‘If you complete all the steps from A to Z, the mission is a success.’
  • plan A

    • One's original plan or strategy.

      ‘plan A having gone horribly wrong, Ferguson used the interval to change his formation’
      Compare with plan B
      • ‘Plan A, business as usual, is no longer a viable option.’
      • ‘I don't know what plan A was, but it evidently failed.’
      • ‘You've got to still have a Plan B if Plan A doesn't work.’
      • ‘Have a plan B in case plan A fails.’
      • ‘Plan A had been for me to travel with Connie on the train, but there were no seats available.’
      • ‘We had Plan A and Plan B and Plan C.’
      • ‘That's plan A, but I've a number of other plans.’
      • ‘I think the only reason you're back now is because Plan A disintegrated and I'm your contingency.’
      • ‘If their coaches are talking differently October 1, you'll know Plan A didn't quite work.’
      • ‘Why not just carry on with Plan A as if nothing has happened?’
      • ‘This is plan A; this is what I plan to do.’
      • ‘However, since football is now a 16-man game, he can bring on talented substitutes if plan A is not working.’
      • ‘Plan A, to propose on Detonator, backfired when she saw the ride on the website and refused to go on it.’
      • ‘We had a review in the first week of the work to see if plan A was still the best way forward.’
      • ‘We can't even resort to Plan B these days because we haven't got a Plan A!’
      • ‘Fortunately, I have appealing contingency plans, but still first I'll apply myself to plan A with all my strength.’
      • ‘Plan A is actually just to turn up on the day and make it up.’
      • ‘Business as usual - Plan A - is clearly not working.’
      • ‘You either continue with plan A, or you look at alternatives.’

Pronunciation

A

/ā//eɪ/

  • 1Ace (used in describing play in bridge and other card games)

    ‘you cash AK of hearts’
  • 2informal A level.

  • 3Ampere(s).

  • 4Ångstrom(s).

  • 5Attack (in designations of US aircraft types)

    ‘an A-10’
  • 6Answer.

    ‘Q: What's the senator's zodiac sign? A: He's a Leo’
  • 7(in personal ads) Asian.