| 1. | the part of a shirt below the waistline. |
| 2. | Journalism. a brief item added at the end of a related newspaper story. Compare follow-up (def. 3b). |
| 3. | quite young and immature in behavior. |
| 4. | Chiefly Midland and Southern U.S. of distant relation, esp. by marriage: some shirttail cousins I'd never met. |
| 5. | Informal. to append or add (an item) to a discussion or writing: The tariff concessions were shirttailed onto the trade bill. |