1. A structure, usually brick or stone, built against a wall for support or reinforcement.
2. Something resembling a buttress, as:
   1. The flared base of certain tree trunks.
   2. A horny growth on the heel of a horse's hoof.
3. Something that serves to support, prop, or reinforce: "The law is by its very nature a buttress of the status quo" (J. William Fulbright).

1. To support or reinforce with a buttress.
2. To sustain, prop, or bolster: "The author buttresses her analysis with lengthy dissections of several of Moore's poems" (Warren Woessner).

[Middle English buteras, from Old French bouterez, from bouter, to strike against, of Germanic origin.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.