The Collaborative International Dictionary of English v.0.48:

Contributor \Con*trib"u*tor\, n.
   One who, or that which, contributes; specifically, one who
   writes articles for a newspaper, magazine, or book.
   [1913 Webster]

WordNet (r) 3.0 (2006):

contributor
    n 1: someone who contributes (or promises to contribute) a sum
         of money [syn: subscriber, contributor]
    2: a writer whose work is published in a newspaper or magazine
       or as part of a book

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "contributor":
   Maecenas, Santa Claus, almoner, almsgiver, angel, assignor,
   awarder, backer, bestower, cheerful giver, conferrer, consignor,
   donator, donor, fairy godmother, feoffor, financer, funder, giver,
   grantor, imparter, lady bountiful, patron, patroness,
   philanthropist, presenter, settler, subscriber, sugar daddy,
   supporter, testate, testator, testatrix, vouchsafer