An engine with twelve cylinders and pistons arranged in a v formation as would be a v6 or v8 etc etc. there are many engines in the v formula usualy with an even number of pistons although notable exceptions are vw's v5 engine. v12 engines are probably most commonly associated with the marque Jaguar.
n. software that is no longer sold or supported by the original publisher / developer, often found as free downloads on the internet because it cannot be obtained elsewhere. Not legal, but often seen as morally acceptable because the company that made it is no longer selling the title, nor releasing it as freeware, therefore abandonware is "keeping the gamealive", so to speak.
Doom II is not abandonware because idstill sells it, while The Incredible Machine is not sold, therefore is abandonware.