"become quiet or calm, become silent," 1821, from Latin quiescere "to rest," from suffixed form of PIE root *kweie- "to rest, be quiet."
Entries linking to quiesce
*kweie-
*kweiə-, also *kwyeə-, Proto-Indo-European root meaning "to rest, be quiet."
It forms all or part of: acquiesce; acquit; awhile; coy; quiesce; quiescent; quiet; quietism; quietude; quietus; quit; quitclaim; quite; quit-rent; quittance; requiescat; requiem; requite; while; whilom.
It is the hypothetical source of/evidence for its existence is provided by: Avestan shaitish "joy," shaiti- "well-being," shyata- "happy;" Old Persian šiyatish "joy;" Latin quies "rest, repose, quiet;" Old Church Slavonic po-koji "rest;" Old Norse hvild "rest."