backstop

中文： 后盾、本垒后挡网、捕手

1. An object or a person put in the rear or in the back of something to reinforce, hold, support.
2. A default arrangement that holds if all else fails.
3. A wall or fence behind home plate.
4. A catcher; the position of catcher. (slang)
5. The player who stands immediately behind the striking base.
6. The longstop. (dated)
7. The wicket-keeper. (dated)
8. Something serving to bolster or support a cover story etc.

复数 backstops