noun / verb
buttress
BUT-ruhs/ˈbʌtrəs/
An external support strengthening a wall.
A heavy stone buttress supports the cathedral's outer wall.

Etymology
Old French botrez named a flying buttress, a support built against a wall. Its apparent connection with bouter, “to thrust against,” gives an image of the support bracing the wall.
In context
another application of the flying buttress is to prop up a leaning wall in danger of collapse
More examples
- New evidence buttressed her argument.
- Several buttresses brace the long wall against outward pressure.
- The reserve fund provides a buttress against unexpected losses.
Forms
buttress · buttresses · buttressed · buttressing
Similar words
- prop
- A general support, while buttress often reinforces from the side.