The Collaborative International Dictionary of English v.0.48:

Retailer \Re*tail"er\, n.
   One who retails anything; as, a retailer of merchandise; a
   retailer of gossip; -- used also of businesses, including
   large corporations; as, Sears, Roebuck is one the the
   country's largest retailers.
   [1913 Webster +PJC]

WordNet (r) 3.0 (2006):

retailer
    n 1: a merchant who sells goods at retail [syn: retailer,
         retail merchant]