Definition:Corollary

A corollary is a proof which is a direct result, or a direct application, of another proof.

It can be considered as being a "proof for free" on the back of a proof which has been paid for with blood, sweat and tears.

The word is ultimately derived from the Latin "corolla", meaning "small garland", or the money paid for it. Hence has the sense "something extra", or "freebie".