Meaning of “first” - Learner’s Dictionary

first

adjective uk us /ˈfɜːst/
BEFORE

A1 coming before all others:

Who was the first person to arrive at the party?
He was nervous on his first day at school.
Her first novel didn't sell very well.
They went abroad last year for the first time since having children.
NUMBER

1st written as a word

IMPORTANT

A2 most important:

Sheila won first prize in the photo competition.
→ See also in the first place

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