Antonyms of adj whimsical

1 sense of whimsical

Sense 1
capricious, impulsive, whimsical -- (determined by chance or impulse or whim rather than by necessity or reason; "a capricious refusal"; "authoritarian rulers are frequently capricious"; "the victim of whimsical persecutions")

INDIRECT (VIA arbitrary) -> nonarbitrary, unarbitrary -- (not subject to individual determination)

Similarity of adj whimsical

1 sense of whimsical

Sense 1
capricious, impulsive, whimsical -- (determined by chance or impulse or whim rather than by necessity or reason; "a capricious refusal"; "authoritarian rulers are frequently capricious"; "the victim of whimsical persecutions")
       => arbitrary (vs. nonarbitrary) -- (based on or subject to individual discretion or preference or sometimes impulse or caprice; "an arbitrary decision"; "the arbitrary rule of a dictator"; "an arbitrary penalty"; "of arbitrary size and shape"; "an arbitrary choice"; "arbitrary division of the group into halves")