n. & v.
n. 1 a a projecting support of stone or brick etc. built against a wall. b a source of help or encouragement (she was a buttress to him in his trouble). 2 a projecting portion of a hill or mountain.
v.tr. (often foll. by up) 1 support with a buttress. 2 support by argument etc. (claim buttressed by facts).
[ ME f. OF (ars) bouterez thrusting (arch) f. bouteret f. bouter BUTT(1) ]