Source : Webster's Revised Unabridged Dictionary (1913)

Quiescent \Qui*es"cent\, a. [L. quiescens, -entis, p. pr. of
   quiescere: cf. F. quiescent. See {Quiesce}.]
   1. Being in a state of repose; at rest; still; not moving;
      as, a quiescent body or fluid.

   2. Not ruffed with passion; unagitated; not in action; not
      excited; quiet; dormant; resting.

            In times of national security, the feeling of
            patriotism . . . is so quiescent that it seems
            hardly to exist.                      --Prof.
                                                  Wilson.

   3. (Gram.) Not sounded; silent; as, y is quiescent in ``day''
      and ``say.''

Quiescent \Qui*es"cent\, n. (Gram.)
   A silent letter. --M. Stuart.

Source : WordNet®

quiescent
     adj 1: not active or activated; "the quiescent level of centimeter
            wave-length solar radiation"
     2: marked by a state of tranquil repose; "the quiescent
        melancholy of the town"
     3: being quiet or still or inactive
     4: causing no symptoms; "a quiescent tumor"