Definitions

1. verb

to weaken or damage the confidence or position of someone or something, especially gradually or secretly

“The scandal began to undermine the politician’s reputation.”

2. noun

an act or instance of secretly damaging or weakening someone’s or something’s confidence or position

“The company’s decision to cancel the project was a major undermine of employee morale.”

3. verb (transitive)

to dig or excavate (a passage, tunnel, etc.)

“The miners had to undermine the rock face to reach the vein of gold.”

4. verb (intransitive)

to dig or excavate (a passage, tunnel, etc.)

“The tunnel undermined the hillside and caused it to collapse.”