To bolster, support.
To serve as backstop for.
A catcher; the position of catcher.
The player who stands immediately behind the striking base.
Something serving to bolster or support a cover story etc.
A thing or a person put in the rear or in the back of something to reinforce, hold, support.
A wall or fence behind home plate.
A default arrangement that holds if all else fails.
The money wagered in gambling
Risks