undermine

undermine — verb

1. to gradually make someone or something weaker, less confident, or less effective

1.verbtransitiveB2
Definition

to gradually make someone or something weaker, less confident, or less effective, especially through repeated criticism, doubt, or subtle actions that eat away at their position or reputation

Example

Stefan's constant criticism began to undermine his daughter's confidence.

collocation: undermine + confidence / trust / authority

The manager's contradictory decisions undermined the team's trust in his leadership.

Common collocations
  • undermine confidence
  • undermine trust
  • undermine authority
  • undermine credibility
  • undermine morale
  • undermine progress
Synonyms
  • weaken

    broader and more neutral, without the implication of gradualness or stealth

  • erode

    emphasises slow, continuous wearing away over time; closer in metaphor to undermine

  • sap

    suggests draining energy or resources from within, often of a person or group

  • undercut

    implies a deliberate competitive act that removes support or advantage

Antonyms
  • strengthen

    direct opposite — to make someone or something stronger

  • bolster

    to support or prop up, especially confidence or morale

  • reinforce

    to make an existing quality or position stronger, often by adding support

Grammar Patterns

undermine + noun phrase

be undermined by + noun phrase

Usage Note

Often appears in passive form ('be undermined by'). The subject is typically a person's actions, words, policies, or external events — not a physical force. For the physical sense of digging or washing away, see sense 2.

Common Mistakes

The rain undermined her confidence.
The constant criticism undermined her confidence.
In the figurative sense, the subject should be a person's actions or words, not a natural force like weather.
The scandal undermined the building.
The scandal damaged the building's reputation.
For physical damage to a structure, use 'damaged' or 'weakened'; 'undermine' is best for a gradual, indirect process.

2. to make the ground or supporting material under a structure weaker by removing i

2.verbtransitiveB2
Definition

to make the ground or supporting material under a structure weaker by removing it from underneath, typically through the action of water, digging, or erosion

Example

Heavy rain had undermined the foundation of the old stone bridge.

passive: be undermined by [natural force]

The river current gradually undermined the riverbank near Lan's farm.

collocation: undermine + riverbank / foundation / base

Common collocations
  • undermine the foundation
  • undermine the riverbank
  • undermine the base
  • undermine the wall
  • undermine the ground
Synonyms
  • erode

    broader term for gradual wearing away by natural forces, often at the surface rather than from underneath

  • wash away

    more specific to water action; describes removal rather than structural weakening

  • excavate

    implies deliberate digging to hollow out; more neutral, less negative

  • hollow out

    describes the result of creating an empty space under something

Antonyms
  • reinforce

    to make stronger by adding material or support

  • fortify

    to strengthen against attack or natural forces

  • shore up

    to prop up or support something at risk of collapse

Grammar Patterns

undermine + noun phrase (physical object)

be undermined by + natural force

Usage Note

Frequently appears in passive constructions. The agent is typically a natural force (water, waves, currents, sea) or human activity (digging, mining, construction). The result is a loss of physical support that can cause collapse.

Common Mistakes

The waves undermined the boat.
The waves undermined the pier.
'Undermine' refers to removing support from under something fixed, not to rocking or destabilising a floating object.

Word family

  • undermining
    nounC1
  • undermined
    adjectiveB2

Synonym discussion

Sense: verb/1

Undermine, weaken, erode, sap, and undercut all describe a loss of strength or effectiveness, but they differ in manner and scope. Undermine suggests a gradual, often hidden process — like water wearing away rock from below — and is most natural when describing damage to confidence, authority, or credibility through indirect actions or repeated criticism. Weaken is broader and more neutral, referring to any reduction in strength, whether physical, emotional, or structural, without implying stealth or gradualness. Erode carries the metaphor of slow, continuous wearing away by external forces such as time, pressure, or familiarity. Sap suggests a draining of vital energy or resources from within. Undercut implies a more deliberate, competitive act that removes support or advantage, often in a professional or strategic context. For example, a manager who publicly questions a team member's judgment undermines their authority; too much overtime can sap their energy; and a rival cutting prices undercuts their market position.

weaken ↗erodesapundercut

Etymology

Old EnglishMiddle EnglishEnglish

Undermine entered English in the 1300s, formed from 'under-' and the verb 'mine' (to dig tunnels). Its original meaning was literal: to dig a tunnel under a wall or fortification to make it collapse during a siege. By the 1600s, the word had developed its figurative sense of weakening by gradual or secret means — a metaphor that remains vivid today in both everyday and political language.