verb
undermine
uhn-duh-MYN
verb
1
To weaken support or confidence gradually, often secretly.
"Constant criticism undermined her confidence."
"Rumors were spreading that could undermine the company's reputation."
2
To wear away the base or foundation of something physically, such as by water or digging.
"Years of flooding had undermined the riverbank."
How to Use Undermine
Learner’s notesIn plain EnglishTo weaken something bit by bit, often without it being obvious at first.
Common mistake
Usually used about damaging trust, authority, or stability — not simply "to defeat."
Common pairings
undermine confidence
undermine authority
undermine efforts
Word Forms
undermined past tense, undermines singular
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Constant criticism _____ her confidence.
Etymology
From under- plus mine, originally meaning to dig a tunnel beneath a wall to bring it down.