Definition of "motiveless" [mo•tive•less]

• Without a motive. (adjective)

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• "Indiscriminate killings in East Rand townships continued over the weekend, with 17 more people losing their lives since Saturday in what yet another police report described as motiveless and faceless violence."
• "A man was seriously ill in hospital after being stabbed in a "motiveless" group attack."
• "A motiveless crime is that step nearer to being a perfect crime."