adjective 1 : marked by inactivity or repose : tranquilly at rest 2 : causing no trouble or symptoms
She was standing on the causeway with her aunt and a group of cousins feeding the chickens, at that quiet moment in the life of the farmyards before the afternoon milking-time. The great buildings round the hollow yard were as dreary and tumbledown as ever, but over the old garden-wall the straggling rose-bushes were beginning to toss their summer weight, and the gray wood and old bricks of the house, on its higher level, had a look of sleepy age in the broad afternoon sunlight, that suited the quiescent time.
— George Eliot, The Mill on the Floss, 1860
Sir Francis Bacon may be responsible for pulling this word from its Latin parentage into its English existence; he wrote in The Advancement of Learning (1605) "For the nature of man doth extremely covet to have somewhat in his understanding fixed and unmovable, and as a rest and support of the mind. And, therefore, as Aristotle endeavoureth to prove, that in all motion there is some point quiescent…." The word traces to the Latin verb quiescere, meaning "to become quiet; rest." Today the English word quiescent is used to mean "tranquilly at rest," or, in medical contexts, "causing no trouble or symptoms." It is also sometimes used to describe silent letters especially in Semitic languages like Hebrew.