English: betterment
Welsh: gwelliant
Subject: Cynllunio
English definition: The amount by which the value of land is increased by development or by the grant of planning permission, or because of the development of neighbouring land.
Welsh definition: Y cynnydd yng ngwerth tir yn sgîl datblygiad neu drwy roi caniatâd cynllunio neu oherwydd datblygiad tir cyfagos.