<p><strong>Noun</strong></p><ul><li>A person's name, or a mark representing it, as signed personally or by deputy, as in subscribing a letter or other document.</li><li>The act of signing a document.</li><li>A sign or set of signs at the beginning of a staff to indicate the key or the time of a piece.</li><li>A song, musical arrangement, sound effect, etc., used as a theme identifying a program.</li><li>Any unique, distinguishing aspect, feature, or mark.</li><li>That part of a written prescription that specifies directions for use.</li><li>A distinctive characteristic or set of characteristics by which a biological structure or medical condition is recognized.</li><li>A printed sheet folded to page size for binding together, with other such sheets, to form a book, magazine, etc.</li><li>A letter or other symbol generally placed by the printer at the foot of the first page of every sheet to guide the binder in folding the sheets and in gathering them in sequence.</li><li>A characteristic trace or sign that indicates the presence of a substance or the occurrence of a physical process or event.</li></ul><p><strong>Adjective</strong></p><ul><li>Serving to identify or distinguish a person, group, etc.: a signature tune.</li></ul>