un ‧ der ‧ pin /ˌʌndəˈpɪn $ -ər-/ BrE AmE verb ( past tense and past participle underpinned , present participle underpinning ) [transitive]
1 . to give strength or support to something and to help it succeed:
the theories that underpin his teaching method
America’s wealth is underpinned by a global system which exploits the world’s poor.
2 . technical to put a solid piece of metal under a wall or house in order to make it stronger
—underpinning noun [uncountable and countable]