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

What makes this emptiness more bothersome is the cavalier way Wingard wields the imagery of rogue, militarized killers wreaking havoc on the American landscape. — Katie Walsh, Los Angeles Times, 4 Sep. 2026

But, though the special effects are killer, what makes the show click is its suspenseful melancholy, as quiet scenes build to jolts so intense that the whole audience screamed. — Rhoda Feng, New Yorker, 4 Sep. 2026

Globally, as a killer, colorectal cancer ranks second only to lung cancer. — Caleb Hellerman, CNN Money, 4 Sep. 2026

From the hotel, there’s a descending trail that leads to an unaffiliated, so-so restaurant with a killer position on a wooden deck built on the rocky shores; go for a limoncello and the sea. — Condé Nast, Condé Nast Traveler, 3 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