knife

American  

[nahyf] / naɪf /

noun

plural

knives

1. an instrument for cutting, consisting essentially of a thin, sharp-edged, metal blade fitted with a handle.

2. a knifelike weapon; dagger or short sword.

3. any blade for cutting, as in a tool or machine.

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verb (used with object)

knifed, knifing

1. to apply a knife to; cut, stab, etc., with a knife.

2. to attempt to defeat or undermine in a secret or underhanded way.

verb (used without object)

knifed, knifing

1. to move or cleave through something with or as if with a knife.

   The ship knifed through the heavy seas.

idioms

1. under the knife, in surgery; undergoing a medical operation.

   The patient was under the knife for four hours.

knife British  

/ naɪf /

noun

1. a cutting instrument consisting of a sharp-edged often pointed blade of metal fitted into a handle or onto a machine

2. a similar instrument used as a weapon

3. to have a grudge against or victimize someone

4. to make a bad situation worse in a deliberately malicious way

5. people are determined to harm or put a stop to someone

   the knives are out for Stevens

6. undergoing a surgical operation

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verb

1. to cut, stab, or kill with a knife

2. to betray, injure, or depose in an underhand way

knife More Idioms  

1. see at gunpoint (knifepoint); under the knife; you could cut it with a knife.

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Other Word Forms

• knifelike
  adjective
• knifer
  noun

Etymology

Origin of knife

before 1100; Middle English knif, Old English cnīf; cognate with Dutch knijf, German Kneif, Old Norse knīfr

Explanation

A knife is a sharp tool that's used for slicing or cutting. We suggest using a knife as a kitchen tool instead of as a weapon. A bread knife has a long, serrated edge, and the blade of a pocket knife folds into its handle so you can safely carry it in your pocket. Surgeons use very small knives to make delicate cuts during operations, and various kinds of knives are sometimes used as weapons. To knife, in fact, is to stab or cut with a knife, almost always in a violent way.

Example Sentences

Knife crime offences were down by 9% to 50,430 and firearms offences fell by 9% to just under 5,000, their lowest since 2003.

From BBC • Jan. 29, 2026

The film, directed by documentarian Alex Gibney, is the companion piece to Rushdie's "Knife," a memoir recounting the harrowing 2022 attack and its aftermath.

From Barron's • Jan. 26, 2026

Knife crime in England and Wales has increased since 2011, according to official government data.

From Barron's • Nov. 2, 2025

Knife skills, too, were given a linguistic beat: “Motion of the ocean” for rocking cuts, “slices, sticks, dices” to map the rhythm of the hand and blade.

From Salon • Sep. 4, 2025

I offer the candy to Grandma Knife, who displays her uneven teeth.

From "Born Behind Bars" by Padma Venkatraman

Related Words

• bayonet
• blade
• cutter
• dagger
• machete
• scalpel
• sickle
• skewer
• sword