antic, coltish, elfish, fay, frisky, frolicsome, larky, playful, rollicking, sportive

coy, kittenishgay, happy, lighthearted, whimsicalenergetic, frolic, jocund, lively, merry, spirited, sprightly, spunky, vivaciousdevilish, impish, knavish, mischievous, pixie(also pixy), rascally, roguishamusing, diverting, enjoyable, entertaining, fun, pleasurabledabbling, frivolous, goofy, silly, triflingdelightful, pleasant, pleasingjesting, jocose, jocular, joking, prankish, teasing

earnest, serious-minded, sober, sobersided

dutiful, responsiblegrave, grim, serious, solemn, somber(or sombre), stern, stolidno-nonsense, priggish, starchy, stuffydecorous, formal, proper, sedate, staidguarded, inhibited, restrained