knife

American  

[nahyf] / naɪf /

noun

knives plural

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)

knifes, present (3rd person singular) knifed, past participle, past knifing present participle

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)

knifes, present (3rd person singular) knifed, past participle, past knifing present participle

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

Derived Forms

• knifer
  noun
• knifelike
  adjective

Inflected Forms

Nouns

• knives
  plural

Participles

• knifing
  present
• knifed
  past

Conjugated Forms

Present

• knife
  simple
• knifes
  simple
• have knifed
  perfect
• has knifed
  perfect
• am knifing
  progressive
• are knifing
  progressive
• is knifing
  progressive
• have been knifing
  perfect progressive
• has been knifing
  perfect progressive

Past

• knifed
  simple
• had knifed
  perfect
• was knifing
  progressive
• were knifing
  progressive
• had been knifing
  perfect progressive

Future

• will knife
  simple
• will have knifed
  perfect
• will be knifing
  progressive
• will have been knifing
  perfect progressive

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

SPF general secretary David Kennedy said Scotland was "absolutely" facing a knife crisis and blamed the loss of some stop-and-search powers.

From BBC • Jul. 7, 2026

“They took some form of knife or blade, and put a 250 foot long gash into the beautiful facade of what took so much work, competence, and money to build and complete,” Trump said.

From The Wall Street Journal • Jun. 21, 2026

With AI, hyperscale customers who know exactly what they want can use Tan’s ASICs as a scalpel, rather than turn to the Swiss Army knife of Nvidia’s general-purpose chips.

From Barron's • Jun. 19, 2026

Junaid Nawaz, a 30-year-old described by Lancashire Police as a British-born local man of Pakistani heritage, has also been charged with possession of a knife in a public place.

From BBC • Jun. 14, 2026

For dinner he ate wild carrots, carefully scraped with his knife.

From "Abel's Island" by William Steig

Related Words

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