the GNU version of the Collaborative International Dictionary of English
adj. Destitute of a motive; not incited by a motive.
The Century Dictionary and Cyclopedia
Having no motive or aim; objectless.
WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
adj. occurring without motivation or provocation
Word Usage
"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."