Meaning of “smear” - Learner’s Dictionary

smear

noun [ C ] uk us /smɪər/
MARK

a dirty mark:

There was a smear of oil on his cheek.
STORY

an unpleasant and untrue story about someone that is meant to harm them, especially in politics:

She dismissed the story as a smear.
a smear campaign

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