The Collaborative International Dictionary of English v.0.48:

Librarian \Li*bra"ri*an\ (l[-i]*br[=a]"r[i^]*an), n. [See
   Library.]
   1. One who has the care or charge of a library.
      [1913 Webster]

   2. One who copies manuscript books. [Obs.] --Broome.
      [1913 Webster]

WordNet (r) 3.0 (2006):

librarian
    n 1: a professional person trained in library science and
         engaged in library services [syn: librarian,
         bibliothec]

Moby Thesaurus II by Grady Ward, 1.0:

91 Moby Thesaurus words for "librarian":
   MC, accountant, amanuensis, archivist, attorney, bailiff,
   bibliognost, bibliographer, biblioklept, bibliolater, bibliomane,
   bibliomaniac, bibliopegist, bibliophage, bibliophile, bibliopole,
   bibliopolist, bibliotaph, bibliothec, bibliothecaire,
   bibliothecary, book agent, book collector, book printer,
   book publisher, book salesman, book-stealer, bookbinder,
   bookdealer, bookkeeper, booklover, bookmaker, bookman, bookseller,
   bookworm, butler, cataloger, chief librarian, clerk,
   college editor, copy editor, croupier, curator, custodian,
   dictionary editor, documentalist, editor, editor-in-chief, emcee,
   engraver, executive editor, factor, filing clerk, guardian,
   housekeeper, juvenile editor, landreeve, library director,
   majordomo, managing editor, marker, master of ceremonies, notary,
   notary public, permissions editor, philobiblist, printer, proctor,
   procurator, production editor, prothonotary, publisher,
   record clerk, recorder, recordist, reference editor,
   reference librarian, register, registrar, scorekeeper, scorer,
   scribe, scrivener, secretary, seneschal, stenographer, steward,
   stonecutter, textbook editor, timekeeper, trade editor