Buttress
Etymology
From Old French "(ars) bouterez" (thrusting arches), from "bouter" (to thrust, push), a word of Germanic origin. The buttress is what pushes back against the thrust of the structure it supports.
noun · /BUH-truhs/
A masonry support built against a wall to resist the outward thrust of an arch, vault, or roof.
What it names
The structural counter-push that holds tall stone buildings up, and its verb sense — to buttress an argument — carries the same idea of shoring something against collapse.
Example
Rows of flying buttresses lean against the cathedral, taking the roof’s weight so the walls could open into glass.
Related idea
A buttress resists an outward thrust from outside the wall; a column, by contrast, carries a downward load straight to the ground from beneath. One pushes back sideways; the other holds up from below.
verb · /BUH-truhs/
To strengthen or support an argument, claim, or position with added reasons or evidence.
What it names
It turns the architectural prop into a figure for reinforcement — shoring up a shaky case the way masonry braces a leaning wall.
Example
He buttressed his proposal with data from three independent studies.
Related idea
Close to corroborate, but broader: to corroborate is to add confirming evidence, while to buttress a case is to prop it up by any means — more reasons, examples, or authority.