The Collaborative International Dictionary of English v.0.48:

Dissident \Dis"si*dent\, n. (Eccl.)
   One who disagrees or dissents; one who separates from the
   established religion.
   [1913 Webster]

         The dissident, habituated and taught to think of his
         dissidenc? as a laudable and necessary opposition to
         ecclesiastical usurpation.               --I. Taylor.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Dissident \Dis"si*dent\, a. [L. dissidens, -entis, p. pr. of
   dissidere to sit apart, to disagree; dis- + sedere to sit:
   cf. F. dissident. See Sit.]
   No agreeing; dissenting; discordant; different.
   [1913 Webster]

         Our life and manners be dissident from theirs.
                                                  --Robynson
                                                  (More's
                                                  Utopia).
   [1913 Webster]

WordNet (r) 3.0 (2006):

dissident
    adj 1: characterized by departure from accepted beliefs or
           standards [syn: dissident, heretical, heterodox]
    2: disagreeing, especially with a majority [syn: dissentient,
       dissenting(a), dissident]
    n 1: a person who dissents from some established policy [syn:
         dissenter, dissident, protester, objector,
         contestant]