plural killers
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.
2
informal
: something that is very difficult
That exam was a (real) killer. = That sure was a killer of an exam.
always used before a noun
chiefly US
1
: causing death or destruction
a killer tornado
2
informal
: very impressive or appealing
She has a killer smile. [=a very attractive smile]
a killer résumé
3
informal
: very difficult
a killer exam
Cite this Entry
“Killer.” Merriam-Webster.com Simple Definition, Merriam-Webster, https://www.merriam-webster.com/simple/killer. Accessed 19 Jun. 2026.
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