Meaning of “irrational” - Learner’s Dictionary

irrational

adjective us uk /ɪˈræʃənəl/

Irrational feelings and actions are based on your emotions and not on good reasons:

irrational behaviour
an irrational fear of flying
irrationality noun [ U ] us uk /ɪˌræʃənˈæləti/
irrationally adverb

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