motiveless
mo·ti·ve·less
adjective
1.
occurring without motivation or provocation
- “motiveless malignity”
- “unprovoked and dastardly attack” F.D.Roosevelt
Origin
From motive + -less.
WordNet 2.1 (Princeton University). Wiktionary (CC BY-SA). WordNet 2.1 Copyright Princeton University. All rights reserved. Wiktionary content is available under the Creative Commons Attribution-ShareAlike Licence.