Meaning of “fat” - Learner’s Dictionary

fat

adjective us uk /fæt/ fatter, fattest
PERSON

A1 Someone who is fat weighs too much:

She eats all the time but never gets fat.

More examples

THICK

thick or large:

a fat book
→ See also fat chance

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