shirttail

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun The part of a shirt that extends below the waist, especially in the back.
• noun A brief addition at the end of a newspaper article.
• adjective Very young.
• adjective Of little value; inadequate or small.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The single or split (then rather plural) bottom part of a shirt, below the waist, especially in the back, which, when not tucked into trousers or other vestment, hangs over the wearer's tail-end, like a tail.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a brief addendum at the end of a newspaper article
• noun fabric forming the tail of a shirt