quiet

noiseless, silent, soundless

mute, speechless, wordless

dead, motionless, quiescent

muffled, muted, quieted

dull, gentle, low, soft

ultraquiet

appropriate, becoming, fit, fitting, proper, suitable

modest, plain, simple, unadorned, undecorated

inconspicuous, unnoticeable, unobtrusive

graceful, handsome, refined, tasteful

drab, mousy (or mousey)

practical, sensible

balmy, clement, equable, gentle, mild, moderate, temperate

clear, cloudless, fair, rainless, sunny, sunshiny, windless

lone, lonely, lonesome, reclusive, solitary

private

calm, peaceable, peaceful, serene, tranquil

dead, silent, still

calm, dreamy, hushed, peaceful, restful, serene, soothing, stilly, tranquil

muffled, muted, softened, toned (down)

lull, pause, respite

silence

mildness, soothingness

comity, concord, harmony

casualness, easygoingness, informality, laid-backness, relaxedness

calm, lull, peace, peacefulness, tranquillity (or tranquility)

dry up

relax, tranquilize (also tranquillize), unwind, zone out

appease, conciliate, hush, mollify, pacify, placate

allay, alleviate, assuage, ease, lay, mitigate, quell, relax, relieve, solace

narcotize, sedate, stupefy