What is Shiv (weapon)?

A shiv, also chiv, schiv, and shivvie, is a homemade knife-like weapon that is commonly associated with prison inmates. The word is possibly derived from the 1670s underworld cant word for "knife," chive. Other sources list the Romani word for the same object, chivomengro, as a more likely origin. The derived verb, shiv means "to stab someone", a shivver being an archaic/mostly unused term for a criminal who attacks victims with a knife. A knife improvised in prison is also often called a shank.