undergird
/ˌʌndəˈgɜːd/verb
with obj.
1- secure or fasten from the underside, especially by a rope or chain passed underneath（尤指用绳链）在底部加固; 由底部支撑。
1.1
- formal provide support or a firm basis for〈正式〉支持; 为…提供坚固基础。