The Collaborative International Dictionary of English v.0.48:

Buttress \But"tress\, v. t. [imp. & p. p. Buttressed (?); p.
   pr. & vb. n. Buttressing.]
   To support with a buttress; to prop; to brace firmly.
   [1913 Webster]

         To set it upright again, and to prop and buttress it up
         for duration.                            --Burke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

buttressing
    n 1: a support usually of stone or brick; supports the wall of a
         building [syn: buttress, buttressing]