whimsical

adjective

1 a whimsical sense of humor:

fanciful, playful, mischievous, waggish, quaint, fantastic, unusual, curious, droll;

eccentric, quirky, offbeat, idiosyncratic, unconventional, outlandish, peculiar, bizarre, weird, odd, freakish;

informal freaky;

British, informal dotty.

2 the whimsical arbitrariness of autocracy:

volatile, capricious, temperamental, impulsive, excitable, fickle, changeable, unpredictable, variable, erratic, quicksilver, mercurial, mutable, inconstant, inconsistent, unstable, unsteady, fluctuating, ever-changing, protean, kaleidoscopic, fluid, wavering, vacillating, wayward;

technical labile.