undermine
/ˌʌndəˈmaɪn; ˌʌndɚ`maɪn/ v[Tn]
1 make a hollow or tunnel beneath (sth); weaken at the base 在（某物）下挖洞或挖通道; 从根基处损害
Badgers had undermined the foundations of the church. 獾在这座教堂的地基处打了洞.
cliffs undermined by the sea 底部被海水毁坏了的峭壁.
2 (fig 比喻) weaken (sth/sb) gradually or insidiously 逐渐削弱或暗中破坏（某事物[某人]）
undermine sb's position, reputation, authority, etc, eg by spreading scandalous rumours 暗中损害某人的地位、 声誉、 威信等（如藉散播诽谤性的谣言）
self-confidence undermined by repeated failures 因屡遭挫折而逐渐削弱的自信心.