The Collaborative International Dictionary of English v.0.48:

Egoist \E"go*ist\, n. [F. ['e]go["i]ste. See Egoism.]
   1. One given overmuch to egoism or thoughts of self.
      [1913 Webster]

            I, dullard egoist, taking no special recognition of
            such nobleness.                       --Carlyle.
      [1913 Webster]

   2. (Philos.) A believer in egoism. Egoistic

WordNet (r) 3.0 (2006):

egoist
    n 1: a conceited and self-centered person [syn: egotist,
         egoist, swellhead]
    2: a self-centered person with little regard for others [syn:
       egocentric, egoist]