crotchet, curiosity, eccentricity, erraticism, idiosyncrasy, individualism, kink, mannerism, oddity, peculiarity, quiddity, quip, singularity, tic, trick, twist

affectation, airsattribute, characteristic, mark, property, traitcustom, habit, pattern, practice(also practise), way, wontaddictionabnormality, neuroticism, perversion, weirdnessdisposition, genius, leaning, partialitybent, inclination, penchant, predilection, predisposition, proclivity, propensity, tendency, turnattitude, character, humor, identity, individuality, nature, personality, temperament