armband
/ˈɑːmbænd/noun
1- a band worn around a person's upper arm to hold up a shirtsleeve or as a form of identification臂章, 袖章。
1.1
- an inflatable plastic band worn around a person's upper arm as a swimming aid（戴在臂上帮助游泳的）塑料充气环（或箍）。