What does killer mean?
A killer is fundamentally someone or something that kills. The literal word commonly denotes a person who deliberately takes another person’s life, but it can also describe a disease, extreme condition, or disaster that causes death or severe harm. In informal usage, however, “killer” is often approving: a killer application, song, outfit, or performance is exceptionally effective, successful, or attractive. It can also refer, sometimes humorously, to a very demanding or exhausting experience. These extended meanings are common in British and American English, especially in advertising, entertainment, technology, and informal conversation. The word’s flexibility allows it to move easily from literal violence to praise, although some speakers may find that contrast jarring. In its most serious sense, it is an unambiguous and often accusatory term; in its extended senses, it is usually playful, promotional, or emphatic rather than solemn.
A person who kills, especially one who deliberately kills another person. By extension, something that causes death, destruction, or severe harm.
"The witness said that the killer had left the building before the police arrived."
The literal sense is serious and commonly associated with murder, homicide, and crime reporting. In figurative use, it can denote a disease, disaster, or other severe hazard.
Informally, exceptionally effective, successful, impressive, or appealing; also, difficult or exhausting.
"The small team has produced a killer interface for managing complex projects."
This informal attributive use is especially common in British and American English, particularly in technology, advertising, entertainment, and informal speech.
The plural refers to multiple people or things that kill, or to multiple exceptionally successful or appealing things in informal use.
"The novel portrays serial killers while examining the social conditions that shape their lives."
From a murderer to a must-have gadget, “killer” has travelled remarkably far from its literal sense.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of killer
The word dates from late Middle English and was formed within English by adding the agent suffix “-er” to “kill,” giving its original sense of “one who kills.” The verb “kill” is itself inherited from Old English and ultimately belongs to a Germanic family of words with cognates in Dutch and German. The modern productive sense “killer app” emerged in computing during the late twentieth century, describing an application so useful or attractive that it becomes the dominant choice for a task.
How killer is actually used
The literal noun is serious and often appears in crime reporting. In informal British and American English, attributive uses such as “killer app,” “killer feature,” and “killer outfit” mean exceptionally effective, successful, impressive, or appealing. “Killer” may also be used informally for a difficult or exhausting experience, as in “that was a killer workout.”