The Collaborative International Dictionary of English v.0.48:

Vendor \Vend"or\ (v[e^]nd"[o^]r), n. [See Vender.]
   A vender; a seller; the correlative of vendee.
   [1913 Webster]

WordNet (r) 3.0 (2006):

vendor
    n 1: someone who promotes or exchanges goods or services for
         money [syn: seller, marketer, vender, vendor,
         trafficker]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "vendor":
   arab, automat, cadger, chapman, cheap-jack, cheap-john, cheapjack,
   coin machine, coin-operated machine, colporteur, coster,
   costermonger, duffer, hawker, higgler, huckster, peddler, roadman,
   sidewalk salesman, slot machine, vending machine



Bouvier's Law Dictionary, Revised 6th Ed (1856):

VENDOR, contracts. A seller. (q.v.) One who disposes of a thing in
consideration of money. Vide Purchaser; Seller.