transitive. To work under, so as to impair or destroy; to undermine. Obsolete.

transitive. figurative. To attack, overcome, ruin, or destroy by slow or secret methods; to undermine. Occasionally with away, down. Now rare.

transitive. To creep in beneath. Also figurative.

transitive. figurative. To infect or corrupt; to consume slowly and secretly like (a) canker.

To weaken, injure, destroy or ruin, surreptitiously or insidiously.

transitive. To corrode (metal), as with rust or verdigris. Also figurative and in figurative contexts. Also occasionally intransitive: to…

figurative with reference to a metaphorical wall, foundation, etc.

figurative. transitive. To penetrate through and through, esp. so as to render hollow, rotten, or weak; to undermine. Frequently in passive.

transitive. To destroy in the manner of termites or white ants; to destroy, undermine, or sabotage. Frequently in political contexts.

transitive. figurative. Originally and chiefly U.S. To attack as though from beneath; to put out of action, ruin, or destroy, esp. in a covert or…

(transitive) to ruin, destroy, or disable deliberately and maliciously (frequently by indirect means).

figurative. To render unstable; to render less firm, to undermine.

In extended uses. transitive. To disrupt, obstruct, or spoil. Cf. to throw a monkey wrench into the machinery at monkey wrench, n. 2.