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

Explanation

To weaken is to become less powerful or strong. When a storm weakens, the wind dies down and the torrential rain becomes a light drizzle. If you weaken physically, your strength diminishes: "I did great at the start of the obstacle course, but my arms began to weaken toward the end and I couldn't climb that last wall." You can also weaken in resolve or spirit, like when your sister's criticism of your art project weakens your confidence about including it in an exhibition. This verb comes from weak and its Germanic root meaning "yield" or "soft."

Example Sentences

The AI model revealed that particle size does affect how quickly these forces weaken.

From Science Daily • Apr. 23, 2026

The leak follows Feldstein Soto’s efforts to weaken the state’s public records law after the release of many police officer photos and other materials, which she demanded be returned.

From Los Angeles Times • Apr. 22, 2026

While the average person does not have the power of a federal judge, they do have the agency to make choices in their own daily lives that can weaken or strengthen civil society.

From Salon • Apr. 21, 2026

Wall Street has worried that AI-native tools will weaken demand for software, which has weighed on legacy software companies like Adobe.

From Barron's • Apr. 20, 2026

When parts of the body aren’t used, they tend to weaken, or shrink, or atrophy.

From "Flying to the Moon: An Astronaut's Story" by Michael Collins

Related Words

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