quietude (n.)

*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."

"uneasy or disturbed state of mind," 1709; from disquiet on model of quietude. Disquietness is from 1530s.