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

Brennan, who creates the megahit Netflix true-crime anthology with prolific producer Ryan Murphy, says writing these seasons about infamous serial killers isn’t the challenge — the hard part is deciding who to make the season’s subject. — Jackie Strause, HollywoodReporter, 18 Sep. 2026

Some of the cases have similarities, but investigators do not yet know whether all nine deaths are linked or whether a serial killer could be involved. — Nimi Princewill, CNN Money, 18 Sep. 2026

Regardless of the gender of its central killer, maybe the most equitable thing Monster could do is stop talking. — Roxana Hadadi, Vulture, 18 Sep. 2026

Perhaps showrunner and co-creator Ian Brennan showed restraint, even foresight, by keeping the Floridian killer out of Season 3’s meta movie storyline. — Ben Travers, IndieWire, 18 Sep. 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