From Old French 'bouterez' (thrusting thing) — literally 'the thing that pushes back' against a wall's outward force.
A projecting structure of stone or brick built against a wall to strengthen or support it; figuratively, a source of support or encouragement.
From Old French 'bouterez' (buttress, literally 'a thrusting thing'), from 'bouter' (to thrust, to push, to strike), from Frankish *bōtan (to beat, to strike) or a related Germanic source. The buttress is thus 'the thing that pushes back' — a structure that counteracts the outward thrust of a wall or vault by pushing against it. The etymology perfectly describes the structural mechanics: a buttress resists lateral forces by applying