Definition of whimsical :
1. Full of, or characterized by, whims; actuated by a whim; having peculiar notions; queer; strange; freakish.
2. Odd or fantastic in appearance; quaintly devised; fantastic.
queer, old-fashioned, archaic, tearaway, uncommon, variable, surprise, unprompted, grotesque, continue, amusing, antiquated, unusual, extraordinary, odd, plain, crotchety, quaint, curious, strange, dated, obsolete, inconstant, unstable, funny, temperamental, singular, imaginative, madcap, brainish, humorous, playful, hysterical, out, ludicrous, inconsistent, hotheaded, change, hilarious, wry, old-time, priceless, bizarre, mercurial, unpredictable, preposterous, low-tech, unsteady, ridiculous, primitive, unmatched, droll, fantastical, uncertain, old-world, freakish, anomalous, eccentric, unique, comic, driving, fancy, fantastic, laughable, impetuous, comical, ticklish, peculiar
capricious (part of speech: adjective)
motiveless (part of speech: adjective)
capricious, careless, random, fleeting, fickle, flitting, ambivalent, impulsive, indecisive, sporadic, wayward, irregular, fanciful, spastic, motiveless, flighty, volatile, chancy, nonsystematic, reasonless, systemless, unmethodical, wandering, rambling, adrift, haphazard, arbitrary
- Mr Carver said, in his whimsical way, that he thought Mrs Bablove should drink and forget it. - "Here and Hereafter", Barry Pain.
- But with a soft entreating wail the music came to an end and there the doctor was, smiling down into my face with his whimsical friendly smile that woke me up all over. - "The Melting of Molly", Maria Thompson Daviess.
- Annie and Mary had come to the kitchen door, Annie with her nose not much the worse for the blow, but with her pretty face very pale from the loss of blood, Mary with the whimsical expression that she always wore when she was taking mental notes of anyone whom she intended to imitate later on. - "Vacation with the Tucker Twins", Nell Speed.