Meaning of “dirty” - Learner’s Dictionary

dirty

adjective uk us /ˈdɜːti/
NOT CLEAN

A2 not clean:

dirty clothes
dirty dishes
OFFENSIVE

talking about sex in a way that some people find offensive:

dirty books/jokes
DISHONEST

dishonest or unfair:

a dirty business
→ See also do sb's dirty work
HARMFUL

containing dangerous substances that may be harmful to the environment:

dirty air

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