motiveless

English

From motive +‎ -less.

motiveless (not comparable)

Without a motive.
This seems to have been a motiveless crime: no money was stolen, and nobody had cause to hate the victim.
- 1834, L[etitia] E[lizabeth] L[andon], chapter XIV, in Francesca Carrara. […], volume II, London: Richard Bentley, […], (successor to Henry Colburn), →OCLC, page 167:
  He was interested in their genuine, yet refined simplicity; and, moreover, the most worn and worldly natures vindicate their humanity by occasional preferences and motiveless likings.