killer
UK: ˈkɪlə | US: ˈkɪlər
n. 1. a person or thing that kills
n. 2. (informal) something extremely effective or impressive
n. 3. (slang) a highly skilled or successful person
The word "killer" originates from the verb "kill," which traces back to Old English cwellan (to murder, destroy), from Proto-Germanic kwaljaną. The suffix "-er" is an agentive suffix in English, derived from Old English -ere, used to form nouns indicating a person or thing that performs an action. Thus, "killer" literally means "one who kills." Over time, its usage expanded informally to describe anything exceptionally effective or impressive.
The police are searching for the killer responsible for the crime.
That new song is a killer—I can't stop listening to it.
She's a killer at chess; she wins every tournament.
The heatwave was a real killer for the crops.
He dressed as a zombie killer for Halloween.