a 1
( an before a vowel sound)
■ determiner
1》 used when mentioning someone or something for the first time; the indefinite article.
↘one single: a hundred.
↘used when mentioning someone unfamiliar: a Mr Smith telephoned.
↘someone like (the name specified).
2》 in, to, or for each; per: petrol prices rose by 3p a litre.
Origin
ME: weak form of OE ān 'one'.
Usage
On the question of using a or an before words beginning with h , see usage at an .
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a 2
■ abbreviation
1》 (in travel timetables) arrives.
2》 atto- (10 -18 ).
3》 Brit. (with reference to sporting fixtures) away.
4》 (used before a date) before. [from L. ante .]
■ symbol ( a ) Physics acceleration.
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a
Physics acceleration.
→ a