Adjective

• S: (adj) mindless, reasonless, senseless (not marked by the use of reason) "mindless violence"; "reasonless hostility"; "a senseless act"
• S: (adj) reasonless (not endowed with the capacity to reason) "a reasonless brute"
• similar to
• antonym
• S: (adj) causeless, reasonless (having no justifying cause or reason) "a senseless, causeless murder"; "a causeless war that never had an aim"; "an apparently arbitrary and reasonless change"