(1) A collection of programs or data files.

(2) A set of ready-made software routines (functions) for programmers. The routines are linked into the program when it is compiled. See class library.

(3) A storage device that handles multiple units of media and provides one or more drives for reading and writing them. For example, a tape library holds multiple tape cartridges and includes a robotic mechanism that moves them in and out of the drive(s).

(4) See data library.