A, a As, as. 1 A is the first letter of the English alphabet. 2 In music, A is the sixth note in the scale of C major. 3 If you get an A as a mark for a piece of work or in an exam, your work is extremely good. 4 A or a is used an abbreviation for words beginning with a, such as acre or answer. 5 People talk about getting from A to B when they are referring generally to journeys they need to make, without saying where the journeys will take them. Cars are for getting people from A to B in maximum safety. a an A or an is the indefinite article. It is used at the beginning of noun groups which refer to only one person or thing. The form an is used in front of words that begin with vowel sounds. 1 You use a or an when you are referring to someone or something for the first time and your listener or reader may not know which particular thing you mean. A waiter entered with a tray … Today youve got a new teacher … I manage a hotel. 2 You use a or an when you are referring to any person or thing of a particular type and do not want to be specific … expensive make-up that we saw being advertised by a beautiful model … bring a sleeping bag … waiting for a bus. 3 You use a or an in front of a noun when that noun follows an adjective, or when the noun is followed by words that describe it more fully. The islanders exhibit a constant happiness with life … He did have a real knowledge of the country. 4 You use a or an when you want to refer to a single type or brand of something. Bollinger RD is a rare, highly prized wine.