25B6; adjective (informal) RELAXED, easy-going, equable, free and easy, casual, nonchalant, insouciant, unexcitable, imperturbable, unruffled, blasé, cool, calm, {cool, calm, and collected}, unperturbed, unflustered, unworried, unconcerned; leisurely, unhurried; stoical, phlegmatic, tolerant; informal unflappable.
uptight.