English: development
Welsh: datblygiad
Subject: Cynllunio
English definition: The carrying out of building, engineering, mining or other operations, in, on, over or under land, or the making of any material change in the use of any buildings or land.
Welsh definition: Cynnal gwaith adeiladau, peirianyddol, cloddio neu weithgareddau eraill yn, ar, dros, neu o dan dir, neu o dan y tir, neu newid mawr yn y defnydd a wneir o unrhyw adeiladau neu dir.