Definition of "knife"

knife

/naɪf/

noun
plural knives
1. A utensil or a tool designed for cutting, consisting of a flat piece of hard material, usually steel or other metal (the blade), usually sharpened on one edge, attached to a handle. The blade may be pointed for piercing.
  Quotations
  Jeff was bent low over the backboard, working with the knife, a steady sawing motion, his shirt soaked through with sweat.
  2007, Scott Smith, The Ruins, page 273
2. A weapon designed with the aforementioned specifications intended for slashing and/or stabbing and too short to be called a sword. A dagger.
3. Any blade-like part in a tool or a machine designed for cutting, such as that of a chipper.
verb
third-person singular simple present knifes, present participle knifing, simple past and past participle knifed
1. (transitive) To cut with a knife.
2. (transitive) To use a knife to injure or kill by stabbing, slashing, or otherwise using the sharp edge of the knife as a weapon.
  Quotations
  One day his sergeant began to cane him, on which, seizing his knife, he knifed the sergeant : he knifed the privates : he knifed until he was finally overpowered, and, brought before a court-martial, was condemned to fifteen years at the galleys.
  1843, The Foreign Quarterly Review, volume 31, Treuttel and Würtz, Treuttel, Jun, and Richter, page 236
  The plane has been hijacked. They've already knifed a guy.
  2012, Robert Biswas-Diener, The Courage Quotient: How Science Can Make You Braver, John Wiley & Sons, page 92
  Naw, they found him in the pissery of some gin mill near the Mohawk West terminal—he'd been knifed.
  2015, Ross H. Spencer, The Fedorovich File, Diversion Books, page 211
3. (intransitive) To cut through as if with a knife.
4. (transitive) To betray, especially in the context of a political slate.
5. (transitive) To positively ignore, especially in order to denigrate; compare cut.