shirttail

noun
  1. 1

    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.

  2. 2

    (by extension) The tail-end or periphery of something.

  3. 3

    A tenuous connection.

  4. 4

    A distant kinship.

  5. 5

    A small portion

  6. 6

    Something small and unimportant.

Source: https://en.wiktionary.org/wiki/shirttail