Meaning of “acid” - Learner’s Dictionary

acid

adjective us uk /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)