A shiv (also chiv or shivvie) or shank is an improvised pointed or bladed prison weapon resembling a knife.
The word shiv is recorded from the 1670s (in the spelling chive) as cant for "knife". The exact spelling shiv is recorded in underworld slang from 1915. The cant word probably derives from the Romani word "blade" (compare Romani "knifeman"). The derived verb to shiv means "to stab (someone) with a shiv", and a shivver is an archaic term for a criminal who attacks victims with a knife.
Since weapons are prohibited in prisons, the intended mode of concealment is central to a shiv's construction. An especially thin handle, for instance, makes it easier to conceal in available cracks or crevices in the prison's construction, or in stacks of objects, such as books, permitted to the prisoners; however, this can also render the shiv difficult to grip and wield. Routine body searches in prison make it difficult to conceal a shiv on one's person on a continuous basis. As well as the prison authorities, it is also desirable to conceal possession of a shiv from members of rival prison populations.
In the United States
The word shank is American prison slang for an improvised stabbing weapon. Shanks can be made in various ways: a razor blade stuck into the melted end of a toothbrush; a metal bucket handle filed into a sharp point; or simply a hank of chicken wire twisted back on itself.
The term apparently originates from the fact that in the 19th century men's boots were (and most work boots still are) often equipped with a shank (that is, a central rib providing arch support) of steel, which could be extracted and improvised into a weapon. This threat was well known to prison guards in the 19th century, as shown by this description from 1882:
In Guiteau's day, the reported slang term was cheeser; but the slang noun shank was in use by 1989.
In institutions managed by the Federal Bureau of Prisons, weapons, sharpened instruments, and knives are considered contraband and their possession is punishable as a highest severity-level prohibited act.
In Britain In Britain, the word shiv may also be spelled chiv, and the word shank has become increasingly used in contemporary British slang and used primarily in gang and street contexts.
In the 1950s, British criminal Billy Hill described his use of a "chiv":
References
"Q. What kind of weapons would you see made down there? A. I would say shanks made out of fence or whatever piece of wire they could make a shank out of."