The Collaborative International Dictionary of English v.0.48:

Conservatism \Con*serv"a*tism\, n. [For conservatism.]
   The disposition and tendency to preserve what is established;
   opposition to change; the habit of mind; or conduct, of a
   conservative.
   [1913 Webster]

WordNet (r) 3.0 (2006):

conservatism
    n 1: a political or theological orientation advocating the
         preservation of the best in society and opposing radical
         changes [syn: conservatism, conservativism]