The Collaborative International Dictionary of English v.0.48:

Quiesce \Qui*esce"\, v. i. [imp. & p. p. Quiesced; p. pr. &
   vb. n. Quiescing.] [L. quiescere, akin to quies rest,
   quiet. See Quiet, a. & n.]
   To be silent, as a letter; to have no sound. --M. Stuart.
   [1913 Webster] Quiescence