Definition of casual:
fooling, laid-back, sporadic, daily, incidental, composed, apathetic, unplanned, nonchalant, assistant, occasional, emeritus, remiss, associate, infrequent, cursory, unwitting, workaday, deep-seated, unceremonious, uninterested, quotidian, boot-cut, free-and-easy, inadvertent, lackadaisical, burning, light, discontinuous, by accident, cooperative, insensible, bitter, from time to time, surprise, antisocial, at one with, relaxed, unsteady, affective, contingent, baggy, periodic, like a bull in a china shop, spastic, incurious, clingy, choppy, at ease, coincidental, (every) now and then/again, brief, routine, sometimes, insouciant, chance, best, accidental, involuntary, impromptu, intermittent, tighten, clerical, unpremeditated, easygoing, ceremonial, depth, collaborative, spotty, adjunct, instinctive, budding, erratic, unremarkable, everyday, designate, arbitrary, catchy, episodic, passing, cool, complacent, button-through, day-to-day, chilled, every so often, disinterested, occasionally, A-line, acutely, relaxed, unintended, easy, calm, blue-collar, irregular, spasmodic, button-down, perfunctory, auxiliary, pococurante, effortless, acting, odd, backless, slipshod, plain, spontaneous, basic, mundane, deep, unceremonious, day-after-day, uncurious, unconcerned, informal, easygoing, natural, indifferent, aperiodic, unrestrained, complacency, deputy, collegiate, day-by-day, careless, creative, blind.
- accidental (part of speech: adjective)
- succinct (part of speech: adjective)
- colloquial (part of speech: adjective)
- "Black Jack", Max Brand.
- "The Chautauqua Girls At Home", Pansy, AKA Isabella M. Alden.
- "Butterflies Worth Knowing", Clarence M. Weed.