1. to weaken or damage something gradually or secretly
2. to dig or wear away the ground beneath something

Examples

• The scandal undermined public trust in the government.
• His constant criticism undermined her confidence.
• The river slowly undermined the bridge’s foundation.
• Gossip can undermine team morale.
• The waves undermined the cliff over many years.
• Poor communication undermined the project’s success.
• Erosion undermined the old stone wall.