undergird \| ̷ ̷ ̷ ̷| ̷ ̷\transitive verb Etymology:under (I) + gird 1.: to gird below : make secure underneath < took measures to undergird the ship — Acts 27:17 (Revised Standard Version) > 2.: to brace up : strengthen, support < faith undergirds moral principles — I.G.Whitchurch >