杀手 literally means 'kill hand' — combining 杀 (shā), meaning 'to kill', and 手 (shǒu), meaning 'hand' or 'person who performs an action'. Together, it forms a noun referring to a person whose job or purpose is to kill others, especially for money or political reasons. It carries strong negative connotations and is commonly used in crime reports, novels, films, and news headlines.

While the term can sometimes appear metaphorically — for example, calling a highly effective virus 'a killer' — its primary usage is literal and serious. It is not used for accidental deaths or self-defense situations; those would involve different terms like 凶手 (perpetrator) or 犯罪嫌疑人 (suspect). In formal writing and speech, 杀手 is neutral in grammatical function but emotionally charged, so tone and context matter greatly.