[determiner] - onea hundreda thousanda milliona dozenRound the table were seated six men and a woman.'A' can also be used after fractions.half a milethree-quarters of an hoursix-tenths of a second'A' can also be used to mean each or every.Take one tablet three times a day.He earns $100 000 a (= in one) year.
AN
Meaning of AN in English
Cambridge English vocab. Кембриджский английский словарь. 2012