Calm

Synonyms Windless, tranquil, serene, pacific, restful, halcyon, still, quiet, peaceful, undisturbed, and balmy.

Synonyms Tranquil, like a millpond, glassy, motionless, unagitated, stilly, still, smooth, flat, waveless, and storm-free.

Synonyms Composure, calmness, sangfroid, poise, self-control, tranquillity, imperturbability, placidness, impassiveness, dispassion, stolidity, unflappability, ataraxia, coolness, self-possession, presence of mind, aplomb, serenity, equanimity, equability, placidity, impassivity, phlegm, cool, and ataraxy.

Synonyms Tranquillity, calmness, quietness, peace, serenity, hush, repose, stillness, quiet, quietude, peacefulness, silence, and restfulness.

Synonyms Soothe, placate, appease, hush, gentle, quell, alleviate, quieten (down), dulcify, pacify, mollify, conciliate, lull, tranquillize, allay, assuage, and square off.

Synonyms Compose oneself, control oneself, keep one's head, cool down, take it easy, get a grip, play it cool, wind down, chill out, stay loose, recover/regain one's composure, pull oneself together, simmer down, cool off, quieten down, keep one's cool, keep one's shirt on, come back down to earth, hang loose, and decompress.