Architecture. A projecting structure of brick, stone, or other material built into or against a wall or building to strengthen or support it. See…

As a collective noun: boundaries.

a type of wharf or (in early use) embankment.

a corbel or a buttress.

A prop or stay (usually carried by a segment of an arch), springing from a pier or other support, and abutting against a structure, for the…

figurative. The action or an act of supporting or strengthening something in the manner of a buttress; the corroboration of a belief, theory, etc…

A buttress or projecting piece of masonry to support and strengthen a wall or terrace. in Architecture.

An arched or ‘flying’ buttress, ‘whose object is to counteract the thrust of the main vault of the edifice’ (Gwilt).

In classical architecture: each of the parts of a pier (pier, n.1 2a) visible between engaged columns or pilasters, typically forming the…

In various uses, related to senses of the verb. A flying buttress.

= arc-boutant, n.