from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A derivative work consisting of two pieces of (generally digital) media joined together, such as a video clip with a different soundtrack applied for humorous effect, or a map overlaid with user-supplied data.
- n. A remix that combines two or more songs from different artists into one track.
- n. a Web application that combines data and/or functionality from more than one source.
From mash up, in turn from mash and up. (Wiktionary)