1. (

• mindless ,
• reasonless ,
• senseless

) not marked by the use of reason; "mindless violence"; "reasonless hostility"; "a senseless act" ;

2. (

• reasonless

) not endowed with the capacity to reason; "a reasonless brute" ;

3. (

• 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" ;