define killer
Learner's definition of KILLER. [count]. 1. : a person or thing that kills someone or something. The police finally captured the killer. [= murderer ]. Heart disease is the leading killer of both men and women. The chemical is used as a weed killer. [+] more examples [-] hide examples [+] Example sentences [-] Hide examples. killer /ËkÉªlÉ/ adjective. killer. /ËkÉªlÉ/. adjective. Learner's definition of KILLER. always used before a noun chiefly US. 1. : causing death or destruction. a killer tornado.