Definition: not sensible or logical
Part of Speech: Adjective
Synonym(s): loony, crazy
Antonym(s): sane, logical
1. When my husband started acting in an irrational manner, I suggested he go see a psychiatrist.
2. The girl started to act irrational because of the medication she was taking.
3. Because of my irrational fear of clowns, I never go to the circus.