sub ‧ struc ‧ ture /ˈsʌbˌstrʌktʃə $ -ər/ BrE AmE noun [countable]
1 . one of the structures (↑ structure 1 (3)) within a society or organization that combines with others to form a whole
2 . a solid base under the ground, that supports a building above the ground ⇨ superstructure