U

under the knife

noun, plural knives [nahyvz] /naɪvz/.

an instrument for cutting, consisting essentially of a thin, sharp-edged, metal blade fitted with a handle.
a knifelike weapon; dagger or short sword.
any blade for cutting, as in a tool or machine.

verb (used with object), knifed, knif·ing.

to apply a knife to; cut, stab, etc., with a knife.
to attempt to defeat or undermine in a secret or underhanded way.

verb (used without object), knifed, knif·ing.

to move or cleave through something with or as if with a knife: The ship knifed through the heavy seas.

Idioms

under the knife, in surgery; undergoing a medical operation: The patient was under the knife for four hours.

noun plural knives (naɪvz)

a cutting instrument consisting of a sharp-edged often pointed blade of metal fitted into a handle or onto a machine
a similar instrument used as a weapon
have one’s knife in someone to have a grudge against or victimize someone
twist the knife to make a bad situation worse in a deliberately malicious way
the knives are out for someone British people are determined to harm or put a stop to someonethe knives are out for Stevens
under the knife undergoing a surgical operation

verb (tr)

to cut, stab, or kill with a knife
to betray, injure, or depose in an underhand way

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. v.1865, from knife (n.). Related: Knifed; knifing. 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. see at gunpoint (knifepoint); under the knife; you could cut it with a knife.