marker

1 a slip (as of paper or cloth) that is attached to something to identify or describe it <the markers on the rock and mineral specimens were old and faded> Synonyms label, tag, ticketRelated Words caption, legend; brand, emblem, hallmark, logo, mark, symbol, trademark; badge, decal, plaque, seal, stamp, sticker

2 something that sets apart an individual from others of the same kind <after many blind dates, he's come to realize that self-absorption is the infallible marker of a real loser> Synonyms affection, attribute, attribution, character, criterion, diagnostic, differentia, feature, fingerprint, hallmark, mark, characteristic, note, particularity, peculiarity, point, property, quality, specific, stamp, touch, traitRelated Words badge, indication, sign; emblem, symbol, token; charm, grace; excellence, merit, virtue; eccentricity, idiosyncrasy, oddity, quirk; individuality, singularity, uniqueness