- a1(an before a vowel sound)determiner1》 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.OriginME: weak form of OE ān 'one'.UsageOn the question of using a or an before words beginning with h, see usage at an.————————a2abbreviation1》 (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.————————aPhysics acceleration.→ a
English new terms dictionary. 2014.