ˈ ̷ ̷ ¦ ̷ ̷ (ˌ) ̷ ̷ noun
Usage: usually capitalized U
Etymology: from u nit
: a measure of the heat transmission through a building part (as a wall or window) or a given thickness of a material (as insulation) with lower numbers indicating better insulating properties — compare r-value herein