Meaning of “acid” - Learner’s Dictionary

acid

adjective uk us /ˈæsɪd/

(also acidic, uk /əˈsɪdɪk/ us ) containing acid, or having similar qualities to an acid:

acid soil
an acid smell/taste
acid remark/comment, etc

an unkind remark that criticizes someone

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