liberalist

from WordNet (r) 3.0 (2006)

liberalist
    n 1: a person who favors a political philosophy of progress and
         reform and the protection of civil liberties [syn:
         {liberal}, {liberalist}, {progressive}] [ant:
         {conservative}, {conservativist}]

from The Collaborative International Dictionary of English v.0.48

Liberalist \Lib"er*al*ist\, n.
   A liberal.
   [1913 Webster]