(n.) The quality or state of being moody; specifically, liability to strange or violent moods.

arbitrariness bouderie caprice capriciousness crankiness crotchetiness dejection desultoriness deviability dumpishness eccentricity erraticism fancifulness fantasticality fickleness flightiness freakishness glumness grimness grumness humorsomeness impulsiveness inconsistency inconstancy instability irregularity melancholy mercuriality moodishness mopishness moroseness motivelessness petulance quirkiness restlessness shiftiness sulkiness sullenness surliness temperamentalness uncertainty undependability unfixedness unpredictability unreliability unsettledness unstableness unsteadfastness unsteadiness variability variation variety wantonness waywardness whimsicality whimsicalness whimsy