A thing or a person put in the rear or in the back of something to reinforce, hold, support.
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 wall or fence behind home plate.
A default arrangement that holds if all else fails.
To bolster, support.
To serve as backstop for.
The shaped part of the bodywork of a car or other vehicle that allows the wheel to be accessed, and in the case of front wheels, enable them to be steered.