noun
Refers to a person who commits murder, especially a hired or political killer. A somewhat formal or literary term.
その政治家は凶手に襲われた。
The politician was attacked by an assassin.
事件の凶手はまだ捕まっていない。
The murderer in the case has not been caught yet.
凶 (bad, evil) + 手 (hand, person). The exact historical derivation is uncertain, but the compound suggests 'evil hand' or 'person who commits a violent act'.