source: By Domaina - Own work based on File:ABO system codominance.svg and File:Autodominant.jpg, CC BY-SA 3.0

a distinguishing quality or characteristic, typically one belonging to a person: 際立った性質や特徴、概して人に属してるもの

｟かたく｠ (性格上･身体上の)特徴, 特性, 特質 (!修飾語と共に用いる)

e.g. he was a letter-of-the-law man, a common trait among coaches.: 彼はコーチの間でよくある特徴の、規則通り実行する男だ。

a genetically determined characteristic.: 遺伝的に決定された特徴

mid 16th century: from French, from Latin tractus ‘drawing, draft’ (see tract1). An early sense was ‘stroke of the pen or pencil in a picture’, giving rise to the sense ‘a particular feature of mind or character’ (mid 18th century).