<p><strong>Noun:</strong></p><ul><li>The part of a shirt below the waistline.</li><li>Journalism: a brief item added at the end of a related newspaper story.</li></ul><p><strong>Adjective:</strong></p><ul><li>Quite young and immature in behavior.</li><li>Chiefly Midland and Southern U.S.: of distant relation, especially by marriage: some shirttail cousins I'd never met.</li></ul><p><strong>Verb (used with object):</strong></p><ul><li>Informal: to append or add (an item) to a discussion or writing: The tariff concessions were shirttailed onto the trade bill.</li></ul>