Meaning of “fib” - Learner’s Dictionary

fib

noun [ C ] uk us /fɪb/ informal

a small lie that is not very important:

Don't tell fibs.
fib verb [ I ] (present participle fibbing, past tense and past participle fibbed)

to say something that is not true

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