Meaning of “underrate” - Learner’s Dictionary

underrate

verb [ T ] uk us /ˌʌndəˈreɪt/

to think that someone or something is not as good as they really are:

Don't underrate her. She's a great tennis player.
underrated adjective

I think he's really underrated as an actor.
→ Opposite overrated

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