1. a. A place in which literary and artistic materials, such as books, periodicals, newspapers, pamphlets, prints, records, and tapes, are kept for reading, reference, or lending. b. A collection of such materials, especially when systematically arranged. c. A room in a private home for such a collection. d. An institution or a foundation maintaining such a collection.
2. A commercial establishment that lends books for a fee.
3. A series or set of books issued by a publisher.
4. A collection of recorded data or tapes arranged for ease of use.
5. Computer Science. A collection of standard programs, routines, or subroutines, often related to a specific application, that are available for general use.
[Middle English librarie, from Anglo-Norman, from Latin librārium, bookcase from neuter of librārius, of books, from liber, libr-, book.]