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

Last but certainly not least, there’s the focus on communicating local relevancy as a differentiator without weakening brand equity and DNA. — Jennifer Weil, Footwear News, 9 Oct. 2026

For now, Dalio said the tightening process is only beginning, with earnings growth still providing support for stocks even as credit conditions start to weaken. — Lee Ying Shan, CNBC, 8 Oct. 2026

Narrowing the spread also weakens the incentive to steer patients toward costlier drugs and to acquire physician practices and infusion clinics — the very behaviors that have made care more expensive. — Casey B. Mulligan, STAT, 8 Oct. 2026

The modified biochar was then inserted between layers of two biodegradable plastics, polylactic acid (PLA) and polybutylene adipate-co-terephthalate (PBAT), therefore creating pathways that could absorb and weaken electromagnetic waves. — Georgina Jedikovska, Interesting Engineering, 8 Oct. 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