weaken

American  

[wee-kuhn] / ˈwi kən /

verb (used with object)

1. to make weak or weaker.

   Synonyms:

   invalidate, minimize, impair, reduce, lower, diminish, lessen, deplete, exhaust, sap, undermine, enervate, debilitate, enfeeble

   Antonyms:

   strengthen

2. Phonetics. to change (a speech sound) to an articulation requiring less effort, as from geminate to nongeminate or from stop to fricative.

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verb (used without object)

1. to become weak or weaker.

   Synonyms:

   sap, undermine, enervate, debilitate, enfeeble, invalidate, minimize, impair, reduce, lower, diminish, lessen, deplete, exhaust

   Antonyms:

   strengthen

weaken British  

/ ˈwiːkən /

verb

1. to become or cause to become weak or weaker

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Other Word Forms

• reweaken verb
• unweakened adjective
• unweakening adjective
• weakener noun

Etymology

Origin of weaken

First recorded in 1520–30; weak + -en ¹

Example Sentences

The amendment has outraged environmentalists, who say it will weaken protections for crucial water sources.

From Barron's • Apr. 8, 2026

The risk/reward of staying in private funds isn’t good because fund performance has started to weaken and there is a risk of higher redemptions in the coming quarters.

From Barron's • Apr. 3, 2026

Car purchases tend to weaken, for example, perhaps because in their mental accounting, people place cars and gasoline into the same spending bucket.

From The Wall Street Journal • Mar. 31, 2026

And, when investors’ trust in the published net asset values starts to weaken, it can trigger a feedback loop of redemption requests.

From MarketWatch • Mar. 31, 2026

The monsoon storm of rage that just burst out of me starts to weaken.

From "Born Behind Bars" by Padma Venkatraman

Related Words

• abate
• decline
• decrease
• depress
• dilute
• diminish
• dwindle
• halt
• impair
• lessen
• lower
• reduce
• sap
• soften
• undermine
• wane