relaxed, at ease, easy-going, equable, free and easy, easy, casual, informal, friendly, nonchalant, insouciant, unexcitable, imperturbable, unemotional, unruffled, blasé, blithe, cool, collected, cool, calm, and collected, calm, composed, self-possessed, level-headed, self-controlled, unperturbed, unflustered, unworried, unconcerned, placid, peaceful, tranquil, serene, low-key, understated, downbeat