Lewis Short
substructÄo (noun F) : substruo
* An under - building, foundation, substructure, Vitr. 1, 5: maxima debet esse cura substructionum,id. 6, 11: maximae,Caes. B. C. 2, 25: insanae,Cic. Mil. 20, 53; 31, 85; Liv. 38, 28; Front. Aquaed. 3, 5 sq.; Col. 1, 5, 9; v. substruo fin.
Charlton T. Lewis, Charles Short, A Latin Dictionary