un·der·pin 
/ˌʌndɚˈpɪn/ verb
un·der·pins; un·der·pinned; un·der·pin·ning /ˌʌndɚˈpɪn/ verb [+ obj] : to strengthen or support (something) from below
▪ a wall underpinned by metal beams — usually used figuratively ▪ a report underpinned by ample research
▪ a wall underpinned by metal beams — usually used figuratively ▪ a report underpinned by ample research
— un·der·pin·ning /ˈʌndɚˌpɪnɪŋ/ noun, plural un·der·pin·nings [count, noncount]
▪ the moral underpinnings [=basis] of the administration's policies
/ˈʌndɚˌpɪnɪŋ/ noun, plural un·der·pin·nings [count, noncount] ▪ the moral underpinnings [=basis] of the administration's policies
