knife

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A cutting instrument consisting of a sharp blade attached to a handle.
2. n. A cutting edge; a blade.
3. v. To use a knife on, especially to stab; wound with a knife.
4. v. Informal To betray or attempt to defeat by underhand means.
5. v. To cut or slash a way through something with or as if with a knife: The boat knifed through the waves.
6. idiom. under the knife Informal Undergoing surgery.

Century Dictionary and Cyclopedia

1. n. A cutting-instrument consisting of a comparatively short blade and a handle, adapted for easy use with the hand. Knives are made in a great variety of shapes, often with several blades which fold into the handle, and for many uses : as, a claspknife, penknife, pocket-knife, bread-knife, fruit-knife, grafting-knife, oyster-knife, splitting-Knife. Many forms of knives are described under their special names in the present work. See also phrases below.
2. n. In a wider sense, any small cutting-tool, or any part of a tool or machine having a sharp edge for cutting or scraping: as, the knives of a mowing-machine, printing-press, meat-chopper, straw-cutter, etc.
3. n. A sword or cutlas; a long cutting-weapon.
4. n. A saddlers' cutting-tool with a sharp convex edge.
5. To stab or kill with a knife.
6. To endeavor to defeat in a secret or underhand way in an election, as a candidate of one's own party. [Political slang, U.S.]

Wiktionary

1. n. 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.
2. n. A weapon designed with the aforementioned specifications intended for slashing and/or stabbing and too short to be called a sword. A dagger.
3. n. Any blade-like part in a tool or a machine designed for cutting, such as the knives for a chipper.
4. v. transitive To cut with a knife.
5. v. transitive To use a knife to injure or kill by stabbing, slashing, or otherwise using the sharp edge of the knife as a weapon.
6. v. intransitive To cut through as if with a knife.
7. v. transitive To betray, especially in the context of a political slate.
8. v. transitive To positively ignore, especially in order to denigrate. compare cut

GNU Webster's 1913

1. n. An instrument consisting of a thin blade, usually of steel and having a sharp edge for cutting, fastened to a handle, but of many different forms and names for different uses.
2. n. A sword or dagger.
3. v. (Hort.) To prune with the knife.
4. v. Low To cut or stab with a knife.
5. v. Slang, U. S. Fig.: To stab in the back; to try to defeat by underhand means, esp. in politics; to vote or work secretly against (a candidate of one's own party).

WordNet 3.0

1. n. edge tool used as a cutting instrument; has a pointed blade with a sharp edge and a handle
2. n. any long thin projection that is transient
3. n. a weapon with a handle and blade with a sharp point
4. v. use a knife on