1. intr. To become quiescent; to subside into.
1833 Wild Sports of West I. 27 Did tired nature quiesce for a moment, I was+roused with a tornado of+sounds. 1888 Howells Annie Kilburn xxx. 330 The village, after a season of acute conjecture, quiesced into+sufferance of the anomaly.

2. intr. Of a letter: To become silent; said of the feeble consonants in Hebrew when their sound is absorbed in that of a preceding vowel.
1828 Stuart Elem. Heb. Lang. (1831) 25 A moveable consonant is one which is sounded, and does not quiesce or coalesce. 1853 J. R. Wolf Practical Heb. Gr. 8 The letters JTUB are said to quiesce in the vowels after which they are placed.
OED2