n. A distinguishing sign, mark, or manifestation; an indicative appearance or characteristic, either physical or mental; a condition or quality significant of something: as, the signatures of a person's temperament seen in his face.n. Specifically An external natural marking upon, or a symbolical appearance or characteristic of, a plant, mineral, or other object or substance, formerly supposed by the Paracelsians (and still by some ignorant persons) to indicate its special medicinal quality or appropriate use.n. The name of a person, or something used as representing his name, affixed or appended to a writing or the like, either by himself or by deputy, as a verification, authentication, or assent (as to a petition or a pledge).n. In Scots law, a writing formerly prepared and presented by a writer to the signet to the baron of exchequer, as the ground of a royal grant to the person in whose name it was presented.n. A letter or figure placed by the printer at the foot of the first page of every section or gathering of a book.n. Hence A sheet; especially, in bookbinders' use, a sheet after it has been folded and is ready to be gathered.n. In musical notation, the signs placed at the beginning of a staff to indicate the key (tonality) and the rhythm of a piece.n. In entomology, a mark resembling a letter; one of the marks of a signate surface.To mark out; distinguish.