(n.) A characteristic peculiar to, and distinguishing, an individual or group; a peculiarity; an eccentricity\.

aberration abnormality animus anomaly aptitude aroma attribute badge banner bent bias brand cachet cast character characteristic conceit configuration constitution crackpotism crank crankiness crankism crotchet crotchetiness cut deviancy deviation device diathesis differentia differential differentness disposition distinctive feature divergence dottiness earmark eccentricity erraticism erraticness feature figure flavor freakiness freakishness grain gust habit hallmark idiocrasy image impress impression inclination index indicant indicator individualism insignia irregularity keynote kidney kink leaning lineaments maggot make makeup mannerism mark marking measure mental set mettle minauderie mind mind-set mold nature nonconformity note oddity odor particularity peculiar trait peculiarity picture predilection predisposition preference proclivity propensity property quality queerness quip quirk quirkiness representation representative savor seal set shape sigil sign signal signature singularity slant smack specialty stamp strain strangeness streak stripe sure sign symptom taint tang taste telltale sign temper temperament tendency token trademark trait trick trick of behavior turn turn of mind twist type unconventionality unnaturalness warp whim whimsicality whimsy