knife

[nahyf]
noun, plural knives [nahyvz] /naɪvz/.
  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.
verb (used with object), knifed, knif·ing.
  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, knif·ing.
  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.

Origin of knife

before 1100; Middle English knif, Old English cnīf; cognate with Dutch knijf, German Kneif, Old Norse knīfr
Related formsknife·like, adjectiveknif·er, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for under the knife

knife

noun plural knives (naɪvz)
  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. have one's knife in someone to have a grudge against or victimize someone
  4. twist the knife to make a bad situation worse in a deliberately malicious way
  5. the knives are out for someone British people are determined to harm or put a stop to someonethe knives are out for Stevens
  6. under the knife undergoing a surgical operation
verb (tr)
  1. to cut, stab, or kill with a knife
  2. to betray, injure, or depose in an underhand way
Derived Formsknifelike, adjectiveknifer, noun

Word Origin for knife

Old English cnīf; related to Old Norse knīfr, Middle Low German knīf
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for under the knife

knife

n.

late Old English cnif, probably from Old Norse knifr, from Proto-Germanic *knibaz (cf. Middle Low German knif, Middle Dutch cnijf, German kneif), of uncertain origin. To further confuse the etymology, there also are forms in -p-, e.g. Dutch knijp, German kneip. French canif "penknife" (mid-15c.) is borrowed from Middle English or Norse.

knife

v.

1865, from knife (n.). Related: Knifed; knifing.

Online Etymology Dictionary, © 2010 Douglas Harper

Idioms and Phrases with under the knife

under the knife

Undergoing surgery, as in He was awake the entire time he was under the knife. The phrase is often put as go under the knife meaning “be operated on,” as in When do you go under the knife? Knife standing for “surgery” was first recorded in 1880.

knife

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

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.