momentum, impulse, impetus, imagination, urge, conceit, notion, impulsion, neural impulse, pulse, freak, bee, changeableness, liking, nervous impulse, mood, crotchet, inclination, maggot, capriciousness, whimsey, quirk, image, idea, humor, boutade, supposition, desire, megrim, nerve impulse, belief, thoughts, predilection, pulsing, pulsation, eccentricity, conception
caprice (part of speech: noun)
motivelessness (part of speech: noun)
arbitrariness, spasticity, fleetingness, volatility, whimsicality, ambivalence, carelessness, indecisiveness, randomness, waywardness, impulsiveness, flightiness, irregularity, fancifulness, fickleness, haphazardness
- She was paying dearly for her mad caprice. - "The Grey Cloak", Harold MacGrath.
- The demands for the produce of agriculture are uniform, they are not under the influence of fashion, prejudice, or caprice. - "On The Principles of Political Economy, and Taxation", David Ricardo.
- As for Walsingham, earnestly a defender of the Netherland cause from the beginning, he was wearied and disgusted with fighting against the Queen's parsimony and caprice. - "Project Gutenberg History of The Netherlands, 1555-1623, Complete", John Lothrop Motley.