Definition of “big” - Learner’s Dictionary

big

adjective uk us /bɪɡ/ (bigger, biggest)
SIZE

A1 large in size or amount:

I come from a big family.
We're looking for a bigger house.
IMPORTANT

A2 important or serious:

Tonight's big game is between Real Madrid and Manchester United.
Buying that car was a big mistake.
your big brother/sister informal
SUCCESSFUL informal

successful or popular:

The programme's been a big hit (= very popular) with young children.
make it big informal

to become very successful or famous

(Definition of “big” from the Cambridge Learner's Dictionary © Cambridge University Press)