Definition from Wiktionary, the free dictionary
Alternative forms 
First attested 1665–1675, probably from Romani chiv (“blade”).
shiv (plural shivs)
- A knife. Usually associated with a makeshift instrument fashioned from something not normally used as a weapon (like a plastic spoon or a toothbrush).
- A woody by-product from processing flax or hemp.
- (computing) A shim, i.e. a small library that transparently intercepts and modifies calls to an API, usually for compatibility purposes.
- To stab someone with a shiv.
- By extension, to stab someone with anything not intended as a stabbing weapon.