Short for library, it is used in the UN*X world to refer to a collection of code objects that are linked into the executable at the last step of compiling, or are linked dynamicly at run-time.
Forgive the speeling of dynamic, and I don't care what you language nazis think, it is pronounced with a short i! Screw you!
Furthermore, GIF is pronounced with a hard G -- even if CompuServe says otherwise!