Meaning of “a” - Learner’s Dictionary

a

determiner (also an) uk us strong // weak /ə/
BEFORE NOUN

A1 used before a noun to refer to a single thing or person but not a particular thing or person or not one that you have referred to before:

I need a new car.
I saw a woman speaking to him.
ONE

A1 one:

a hundred dollars
EVERY/EACH

A1 every or each:

Take one tablet three times a (= each) day.
TYPE

A1 used to say what type of thing or person something or someone is:

It's a guinea pig.
She's a doctor.
AN ACTION

A2 used before some action nouns when referring to one example of the action:

Take a look at this.
UK I'm just going to have a wash.
TWO NOUNS

A2 used before the first of two nouns that are often used together:

a cup and saucer
AMOUNTS

A2 used before some phrases saying how much of something there is:

a few days
a bit of sugar
NAME

used before a person's name when referring to someone you do not know:

There's a Ms Leeming to see you.

(Definition of “a determiner” from the Cambridge Learner’s Dictionary © Cambridge University Press)