The Collaborative International Dictionary of English v.0.48:

Sedan \Se*dan"\, n. [Said to be named from Sedan, in France,
   where it was first made, and whence it was introduced into
   England in the time of King Charles I.]
   A portable chair or covered vehicle for carrying a single
   person, -- usually borne on poles by two men. Called also
   sedan chair.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sedan chair
    n 1: a closed litter for one passenger [syn: sedan, sedan
         chair]