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

Meanwhile, Kane’s other horror prequel series Crystal Lake is now available to stream on Peacock, telling the origin story of Friday the 13th killer Jason Voorhees and mother Pam (Linda Cardellini). — Glenn Garner, Deadline, 16 Oct. 2026

Detectives worked to identify the killers, but the case eventually went cold. — Milena Malaver, Miami Herald, 16 Oct. 2026

No agents died in the real-life incident, and whether Good’s car ever posed a threat to her killer, Jonathan Ross, remains widely disputed. — Alison Foreman, IndieWire, 15 Oct. 2026

The result is Unhinged, a first-person horror game in which Ava (voiced by Zoë Kravitz) must flee a killer through a powerless apartment building. — Matthew Huff, Time, 15 Oct. 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