The Collaborative International Dictionary of English v.0.48:
Undergird \Un`der*gird"\, v. t. To bind below; to gird round the bottom. [1913 Webster] They used helps, undergirding the ship. --Acts xxvii. 17. [1913 Webster]WordNet (r) 3.0 (2006):
undergird v 1: lend moral support to 2: make secure underneath; "undergird the ship" [syn: undergird, brace up]