n. 25B6; adjective
she seemed very calm : SERENE, tranquil, relaxed, unruffled, unperturbed, unflustered, untroubled; equable, even-tempered; placid, unexcitable, unemotional, phlegmatic; composed, {cool, calm, and collected}, cool-headed, self-possessed; informal unflappable, unfazed.
the night was calm : WINDLESS, still, tranquil, quiet.
the calm waters of the lake : TRANQUIL, still, smooth, glassy, like a millpond; poetic/literary stilly.
excited, nervous, stormy.
25B6; noun
calm prevailed : TRANQUILLITY, stillness, calmness, quiet, quietness, quietude, peace, peacefulness.
his usual calm deserted him : COMPOSURE, coolness, calmness, self-possession, sangfroid; serenity, tranquillity, equanimity, equability, placidness, placidity; informal cool, unflappability.
25B6; verb
I tried to calm him down : SOOTHE, pacify, placate, mollify, appease, conciliate; Brit. quieten (down); Austral. square off; poetic/literary dulcify.
she forced herself to calm down : COMPOSE ONESELF, recover/regain one's composure, control oneself, pull oneself together, simmer down, cool down/off, take it easy; Brit. quieten down; informal get a grip, keep one's shirt on, wind down; N. Amer. informal chill out, hang/stay loose, decompress.
excite, upset.