armband

/AA1 R M B AE0 N D/
noun
  1. 1

    A band worn around the arm, usually to symbolize protest or mourning.

  2. 2

    A band worn around the arm of the captain of a team.

  3. 3

    An inflatable band worn round the arms to keep afloat in water

Synonyms

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