underbuildingEtymologyFrom underbuild (“to build beneath, lay a foundation for”), equivalent to underbuild + -ing.underbuilding means A substructure; foundation; infrastructure. Lexicurio rates it Sui generis — a strength score of 87 out of 100.nounA substructure; foundation; infrastructure.“It appears from the evidence that although the Dean of Guild authorities considered the defective underbuilding to have been sufficient to warrant the demolition of the wall, it must have otherwise been in a weak and decayed condition.”