thumb|Shivs hidden in a book, Hong Kong
A shiv (also chiv 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 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
thumb|A display of contraband weapons at the [[Old Idaho Penitentiary museum]]
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;
In Britain
In Britain, the word shiv may also be spelled chiv,
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