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

If Russia moves in this direction, a nuclear detonation in low-Earth orbit could be the ultimate Starlink killer. — Stephen Clark, ArsTechnica, 16 July 2026

Scattered on the dunes, the surviving population of Gaza was reduced to bare existence, subject to unrelenting hunger and thirst under the ever-present hum of killer drones and bomber jets. — Literary Hub, 16 July 2026

And the trailer shows how idyllic the four victims’ college experience was until Bryan Kohberger (who has pled guilty to the murders) seemingly picked them at random to act out his serial-killer obsession. — Bethy Squires, Vulture, 15 July 2026

Malaria is one of the great historical killers for humanity, causing 610,000 deaths in 2024 alone, according to the World Health Organization. — Jacopo Prisco, CNN Money, 15 July 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