killer

1 of 2

noun

kill·​er ˈki-lər 

1

: one that kills

2

: killer whale

3

a

: one that has a forceful, violent, or striking impact

b

: one that is extremely difficult to deal with

killer

2 of 2

adjective

1

: strikingly impressive or effective

a killer smile

a killer résumé

2

: extremely difficult to deal with

a killer fastball

also : causing death or devastation

a killer tornado

Synonyms of killer

Noun

• headache
• job

Adjective

• lethal
• deadly
• fatal

Examples of killer in a Sentence

Noun

Heart disease is the leading killer of both men and women.

The chemical is used as a weed killer.

Adjective

killer viruses that claimed millions of lives

a killer exercise program guaranteed to whip you into shape

Recent Examples on the Web

Noun

The pools are worth the visit alone—killer views, and plenty of space to hop around to keep the scenery fresh. — Condé Nast, Condé Nast Traveler, 15 Aug. 2026

When his friend Tetsuo (Nozomu Sasaki) is abducted by military elites bent on turning him into a supernatural killer, Kaneda tries to rescue him. — David Faris, TheWeek, 14 Aug. 2026

Has playing Bret or playing around in the world of The Shards rubbed off on you in terms of going down rabbit holes about Hollywood’s history around cults and serial killers? — Jackie Strause, HollywoodReporter, 14 Aug. 2026

Investigators examined the patterns of other serial killers who passed through Missouri at the time and turned up nothing. — Dateline Nbc, NBC news, 13 Aug. 2026

Word History

First Known Use

Noun

15th century, in the meaning defined at sense 1

Adjective

1939, in the meaning defined at sense 2

Phrases Containing killer

• killer app
• killer bee
• killer cell
• killer instinct
• killer T cell
• killer T lymphocyte
• killer whale
• lady-killer
• natural killer cell
• pain-killer
• time killer

Rhymes for killer

• biller
• chiller
• driller
• filler
• hilar
• hiller
• pillar
• quiller
• siller
• spiller
• stiller
• thriller

Kids Definition

killer

1 of 2 noun

ˈkil-ər

1

: one that kills

2

: killer whale

killer

2 of 2 adjective

1

: strikingly impressive or effective

a killer smile

2

: extremely difficult

a killer exam

also : causing death or devastation

a killer tornado