Exact historical dictionary sense
Quiet in Webster's 1913 dictionary
The 1913 record labels quiet as adjective. Its source-bounded etymology and selected historical definition appear below.
[L. quietus, p. p. pf quiescere to rest, keep quiet; akin to quies rest, and prob. to E. while, n. See While, and cf. Coy, a., Quiesce, Quietus, Quit, a., Quite, Requiem.]
Cross-verified historical senseIn Webster's Revised Unabridged Dictionary (1913), "quiet" is labeled adjective. Its etymology is recorded as: "[L. quietus, p. p. pf quiescere to rest, keep quiet; akin to quies rest, and prob. to E. while, n. See While, and cf. Coy, a., Quiesce, Quietus, Quit, a., Quite, Requiem.]" The selected historical definition says: "In a state of rest or calm; without stir, motion, or agitation; still; as, a quiet sea; quiet air."