Definitions for shirttailˈʃɜrtˌteɪl
Random House Webster's College Dictionary
the part of a shirt below the waistline.
(adj.)immature in behavior.
Category: Common Vocabulary
Midland U.S. of distant relation, esp. by marriage.
Category: Common Vocabulary, Dialect
(v.t.)to append or add (an item) to a discussion or writing.
Category: Common Vocabulary, Informal
Origin of shirttail:
a brief addendum at the end of a newspaper article
fabric forming the tail of a shirt
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.