I. but ‧ tress 1 /ˈbʌtrəs/ BrE AmE noun [countable]
[ Date: 1300-1400 ; Language: Old French ; Origin: boterez , from boter ; ⇨ ↑ butt 2 ]
a brick or stone structure built to support a wall
II. buttress 2 BrE AmE verb [transitive] formal
to support a system, idea, argument etc, especially by providing money:
The evidence seemed to buttress their argument.