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.
n A weapon designed with the aforementioned specifications intended for slashing and/or stabbing and too short to be called a sword. A dagger.
n Any blade-like part in a tool or a machine designed for cutting, such as the 'knives' for a chipper.
v (transitive) To cut with a 'knife'.
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.
v (intransitive) To cut through as if with a 'knife'.