n. A structure, usually brick or stone, built against a wall for support or reinforcement.n. Something resembling a buttress, as:n. The flared base of certain tree trunks.n. A horny growth on the heel of a horse's hoof.n. Something that serves to support, prop, or reinforce: "The law is by its very nature a buttress of the status quo” ( J. William Fulbright). v. To support or reinforce with a buttress.v. To sustain, prop, or bolster: "The author buttresses her analysis with lengthy dissections of several of Moore's poems” ( Warren Woessner).