The Collaborative International Dictionary of English v.0.48:

Self-conscious \Self`-con"scious\, a.
   1. Conscious of one's acts or state as belonging to, or
      originating in, one's self. "My self-conscious worth."
      --Dryden.
      [1913 Webster]

   2. Conscious of one's self as an object of the observation of
      others; as, the speaker was too self-conscious.
      [1913 Webster]

WordNet (r) 3.0 (2006):

self-conscious
    adj 1: aware of yourself as an individual or of your own being
           and actions and thoughts; "self-conscious awareness";
           "self-conscious about their roles as guardians of the
           social values"- D.M.Potter [syn: self-conscious, self-
           aware]
    2: excessively and uncomfortably conscious of your appearance or
       behavior; "self-conscious teenagers"; "wondered if she could
       ever be untidy without feeling self-conscious about it"

Moby Thesaurus II by Grady Ward, 1.0:

41 Moby Thesaurus words for "self-conscious":
   affected, anxious, apprehensive, artificial, awkward, bashful,
   confused, conscious, coy, demure, diffident, embarrassed,
   exhibitionist, formal, hesitant, ill at ease, inarticulate,
   insecure, mannered, modest, mousy, nervous, ostentatious, prim,
   reserved, retiring, self-effacing, shamefaced, shamefast, sheepish,
   shrinking, shy, skittish, stammering, stiff, stilted, timid,
   timorous, uncomfortable, uneasy, unsure