weaken

verb

weak·​en ˈwē-kən How to pronounce weaken (audio)
weakened; weakening
ˈwēk-niŋ,
ˈwē-kə- How to pronounce weaken (audio)
; weakens

transitive verb

1
: to make weak : lessen the strength of
2
: to reduce in intensity or effectiveness

intransitive verb

: to become weak
weakener
ˈwēk-nər
ˈwē-kə- How to pronounce weaken (audio)
noun
Choose the Right Synonym for weaken

weaken, enfeeble, debilitate, undermine, sap, disable mean to lose or cause to lose strength or vigor.

weaken may imply loss of physical strength, health, soundness, or stability or of quality, intensity, or effective power.

a disease that weakens the body's defenses

enfeeble implies a condition of marked weakness and helplessness.

enfeebled by starvation

debilitate suggests a less marked or more temporary impairment of strength or vitality.

the debilitating effects of surgery

undermine and sap suggest a weakening by something working surreptitiously and insidiously.

a poor diet undermines your health
drugs had sapped his ability to think

disable suggests bringing about impairment or limitation in a physical or mental ability.

disabled by an injury sustained at work

Examples of weaken in a Sentence

The disease weakens the immune system. Some are concerned that the increase in taxes will weaken the economy. The beams had been weakened by water damage. efforts to weaken environmental laws The recent setbacks have not weakened our resolve. These kinds of contradictions weaken your argument. The disease causes the immune system to weaken. The dollar has continued to weaken against the euro. Lower interest rates have weakened the dollar.
Recent Examples on the Web
Examples are automatically compiled from online sources to show current usage. Read More Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.
Since then, a series of shifts has reshaped the Middle East and weakened Iran and its proxies, the war in Gaza, Israel's decimation of the leadership of Hezbollah in Lebanon, the collapse of the Syrian regime, and now Israel's surprise attack. / Cbs News, CBS News, 15 June 2025 Should the economy unexpectedly weaken, larger and sooner cuts are possible. Simon Moore, Forbes.com, 15 June 2025 Hezbollah was weakened by last year’s fighting and after losing a major supply route for Iranian weapons with the fall of Syrian President Bashar Assad, a key ally, in a lightning rebel offensive in December. Abby Sewell, Los Angeles Times, 14 June 2025 Israeli Prime Minister Benjamin Netanyahu survived a vote to dissolve his government, but was left weakened. Ben Smith, semafor.com, 13 June 2025 See All Example Sentences for weaken

Word History

First Known Use

circa 1529, in the meaning defined at transitive sense 1

Time Traveler
The first known use of weaken was circa 1529

Cite this Entry

“Weaken.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/weaken. Accessed 18 Jun. 2025.

Kids Definition

weaken

verb
weak·​en ˈwē-kən How to pronounce weaken (audio)
weakened; weakening ˈwēk-(ə-)niŋ How to pronounce weaken (audio)
: to make or become weak or weaker

More from Merriam-Webster on weaken

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