The Collaborative International Dictionary of English v.0.48:

Reticence \Ret"i*cence\, n. [L. reticentia: cf. F.
   r['e]ticence.]
   1. The quality or state of being reticent, or keeping
      silence; the state of holding one's tonque; refraining to
      speak of that which is suggested; uncommunicativeness.
      [1913 Webster]

            Such fine reserve and noble reticence. --Tennyson.
      [1913 Webster]

   2. (Rhet.) A figure by which a person really speaks of a
      thing while he makes a show as if he would say nothingon
      the subject.
      [1913 Webster]

WordNet (r) 3.0 (2006):

reticence
    n 1: the trait of being uncommunicative; not volunteering
         anything more than necessary [syn: reserve, reticence,
         taciturnity]