Calm

peaceful, tranquil, untroubled, retired; see calm 1, 2, withdrawn.

Silent

hushed, muffled, noiseless, still, stilled, mute, muted, low, soft, inaudible, soundless, dumb, quieted, speechless, unspeaking, mum, quiescent, taciturn, reserved, reticent, unuttered, unexpressed, close-mouthed, close, tight-lipped, uncommunicative, secretive.

Motionless

unruffled, still, placid, level; see calm 2, smooth 1.

Unostentatious

subdued, unobtrusive, unpretentious, understated; see modest 2.

Rest

calm, tranquillity, relaxation; see peace 2, rest 1.

Silence

hush, stillness, speechlessness; see silence 1.

To make calm

calm, cool, relax, compose, tranquilize, soothe, comfort, satisfy, pacify, mollify, placate, assuage, console, subdue, reconcile, gratify, calm down, soften, moderate, smooth, ameliorate, allay, quell, becalm, lull, appease, restrain, palliate, sober, slacken; see also comfort, ease 1, 2.

Antonyms excite*, irritate*, agitate. *

To make silent

hush, still, deaden, silence, soften, mute, tone down, lower the sound level, muffle, stifle, smother, gag, muzzle, stop, check, restrain, suppress, break in, cut short, preclude, confute, repress, refute, confound, answer, quell, insulate, dampen, shush, shut up*, stop the mouth*, floor*, put the lid on*, button up*, choke off*, put the kibosh on*, put the stopper on*, squelch*. *

Antonyms sound*, ring*, cause to sound.