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

Wallace was leaving a music industry party at the Petersen Automotive Museum on March 9, 1997, sitting in the front passenger seat of a Chevrolet Suburban, when his killer pulled up alongside in a dark Chevy Impala. — Richard Winton, Los Angeles Times, 21 Aug. 2026

Some weeks the flashbacks are momentum-killers, interrupting the intense drama in Silo 18. — Noel Murray, Vulture, 21 Aug. 2026

The trailer also promises to touch on how then-contemporary thoughts of women as too innocent to murder helped Lizzie get acquitted, and teases the incorporation of other stories of female killers throughout history. — Wilson Chapman, IndieWire, 20 Aug. 2026

The stories of two high schoolers, Jules and Quinn, entwine on May 1, the day a serial killer attacks one of them. — The Week Us, TheWeek, 20 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