Source : Webster's Revised Unabridged Dictionary (1913)

Library \Li"bra*ry\ (l[imac]"br[asl]*r[y^]), n.; pl. {Libraries}
   (-r[i^]z). [OE. librairie, F. librairie bookseller's shop,
   book trade, formerly, a library, fr. libraire bookseller, L.
   librarius, from liber book; cf. libraria bookseller's shop,
   librarium bookcase, It. libreria. See {Libel}.]
   1. A considerable collection of books kept for use, and not
      as merchandise; as, a private library; a public library.

   2. A building or apartment appropriated for holding such a
      collection of books. --Holland.

Source : WordNet®

library
     n 1: a room where books are kept; "they had brandy in the
          library"
     2: a collection of literary documents or records kept for
        reference or borrowing
     3: a depository built to contain books and other materials for
        reading and study [syn: {depository library}]
     4: (computing) a collection of standard programs and
        subroutines that are stored and available for immediate
        use [syn: {program library}, {subroutine library}]
     5: a building that houses a collection of books and other
        materials

Source : Free On-Line Dictionary of Computing

library
     
         A collection of {subroutines} and
        {functions} stored in one or more files, usually in compiled
        form, for linking with other programs.  Libraries are one of
        the earliest forms of organised {code reuse}.  They are often
        supplied by the {operating system} or {software development
        environment} developer to be used in many different programs.
        The routines in a library may be general purpose or designed
        for some specific function such as three dimensional animated
        graphics.
     
        Libraries are linked with the user's program to form a
        complete {executable}.  The linking may be {static linking}
        or, in some systems, {dynamic linking}.
     
        (1998-11-21)