See capricious in Webster's New World Roget's A-Z Thesaurus II
adjective
Determined or marked by whim or caprice rather than reason:
arbitrary, whimsical. See surpriseFollowing no predictable pattern:
changeable, erratic, fantastic, fantastical, fickle, freakish, inconsistent, inconstant, mercurial, temperamental, ticklish, uncertain, unpredictable, unstable, unsteady, variable, volatile, whimsical. See change, continue
Learn more about capricious