1: not any
particular or certain one of a class or group:
2: a certain; a
particular:
3: another; one typically resembling:
4: one (used before plural nouns that are preceded by a quantifier singular in form): a hundred men (compare hundreds of men); a dozen times (compare dozens of times).
5:
indefinitely or nonspecifically (used with adjectives expressing number):
6: one (used before a noun expressing quantity):
1: a man; a
chemical; a house.
2: one at a time; two of a kind; A
Miss Johnson called.
3: a Cicero in
eloquence; a Jonah.
5: a great many years; a few stars.
6: a yard of ribbon; a score of times.