weaken

1 of 2

verb

weak·​en ˈwē-kən 

weakened; weakening

ˈwēk-niŋ, 

ˈwē-kə-  ; 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- 

noun

weakener

2 of 2

noun

weak·​en·​er -k(ə)nə(r) 

plural -s

: one that weakens

Synonyms of weaken

Verb

• soften
• injure
• debilitate

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

Verb

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

Verb

However, consuming large amounts—such as those used in studies where up to 1/2 cup was consumed daily—can start to weaken and damage tooth enamel. — Md Published, Verywell Health, 10 Aug. 2026

Apple’s market dominance is built around September; moving away from tradition would upset the ecosystem supporting the launch and risk weakening the iPhone’s dominant position. — Ewan Spence, Forbes.com, 10 Aug. 2026

El Niño is a climate pattern characterized by warmer ocean waters in the central and eastern tropical Pacific Ocean, coupled with changing atmospheric conditions, in which the typical east-to-west trade winds weaken or even reverse. — Los Angeles Times, 10 Aug. 2026

Last year, a key vaccine advisory panel to the Centers for Disease Control and Prevention also weakened recommendations for the MMRV shot for children under age 4. — Annika Kim Constantino,jacob Pramuk, CNBC, 10 Aug. 2026

Word History

First Known Use

Verb

circa 1529, in the meaning defined at transitive sense 1

Rhymes for weaken

• beacon
• deacon
• archdeacon
• mohican

Kids Definition

weaken

verb

weak·​en ˈwē-kən 

weakened; weakening ˈwēk-(ə-)niŋ 

: to make or become weak or weaker