Shiv (possibly from the Romani word chivomengro, "knife"), also chiv, is a slang term for any sharp or pointed implement used as a knife-like weapon. The Oxford English Dictionary suggests shive, a razor, documented in 1915, as the root word. In the 1920s, "shiv" was also a common slang term for a bladed weapon, mostly a knife. In the United States, an improvised prison knife is also often called a shank.
The word in practical usage is frequently used when referring to an improvised bladed weapon. Shivs are commonly made by inmates in prisons across the world. A shiv can be anything from a glass shard with fabric wrapped around one end to form a handle, to a razor blade stuck in the end of a toothbrush. Synonyms include shank, chiv, and chib (from Scottish slang, as exemplified in the novel Trainspotting). These terms, along with "shiv", can be used either as a noun or a transitive verb, referring to the weapon or the act of attacking with such a weapon respectively.
In the 1950s, British criminal Billy Hill described his use of the shiv:
"I was always careful to draw my knife down on the face, never across or upwards. Always down. So that if the knife slips you don't cut an artery. After all, chivving is chivving, but cutting an artery is usually murder. Only mugs do murder."