We don't have synonyms for shirt tail yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are shirttail, shirt-tail and shirt tails.
(N) :
a mid-19th-century street gang based in the Five Points slum in Manhattan, New York, United States, who wore their shirts on the outside of their pants as 19th-century Chinese laborers would dress as a form of insignia and as a sign of gang group affiliation.
(N) :
a mid-19th-century street gang based in the Five Points slum in Manhattan, New York, United States, who wore their shirts on the outside of their pants as 19th-century Chinese laborers would dress as a form of insignia and as a sign of gang group affiliation.