weaken

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

Synonyms of weaken

• 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

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

Hezbollah was severely weakened in the last war that ended in November 2024, and Lebanon subsequently elected Aoun and Prime Minister Nawaf Salam, who committed to disarming Hezbollah and other non-state armed groups in the country. — ABC News, 17 Sep. 2026

The coming-of-age experience—friendships, independence, experimentation—has become less obviously dependent on the campus surrounding it, partly because college’s monopoly on exposure to a wider world weakened. — Ian Bogost, The Atlantic, 17 Sep. 2026

The ridge will eventually weaken, with cooler and drier air finally pushing south around Wednesday of next week. — Ron Smiley, CBS News, 17 Sep. 2026

Measles can also weaken the central nervous system and immune system, resulting in serious disease or death years later. — Jen Christensen, CNN Money, 16 Sep. 2026

Word History

First Known Use

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