strengthen

American  

[strengk-thuhn, streng-, stren-] / ˈstrɛŋk θən, ˈstrɛŋ-, ˈstrɛn- /

verb (used with object)

1. to make stronger; give strength to.

   Synonyms:

   support, fortify, reinforce, buttress

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

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verb (used without object)

1. to gain strength; grow stronger.

strengthen British  

/ ˈstrɛŋθən /

verb

1. to make or become stronger

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Other Word Forms

• overstrengthen verb
• prestrengthen verb (used with object)
• restrengthen verb
• strengthener noun
• strengtheningly adverb
• unstrengthened adjective
• unstrengthening adjective

Etymology

Origin of strengthen

First recorded in 1250–1300, strengthen is from the Middle English word strengthnen. See strength, -en ¹

Example Sentences

This new crisis will again strengthen the resolve of European countries and Canada to bolster their own defences and depend on themselves for their own security.

From BBC • Apr. 1, 2026

While supporters argue that restarting drilling would strengthen security and energy independence, experts interviewed by AFP emphasised major constraints for both oil and gas.

From Barron's • Apr. 1, 2026

“We’ve taken steps to improve performance, strengthen free cash flow, and offset dilution, and will continue to evaluate actions that drive long-term value for all stockholders.”

From The Wall Street Journal • Mar. 31, 2026

These tube-like materials can strengthen polymers and metals or guide the movement of ions in batteries and desalination systems with far less resistance.

From Science Daily • Mar. 31, 2026

She gave me a new kind of medicine to give him each night to help strengthen his lungs.

From "A Mango-Shaped Space" by Wendy Mass

Related Words

• bolster
• build up
• enhance
• enlarge
• establish
• extend
• heighten
• increase
• intensify
• invigorate
• reinforce
• restore
• set up
• step up
• support
• sustain
• toughen