breakthrough

1 of 2

noun

break·​through ˈbrāk-ˌthrü How to pronounce breakthrough (audio)
plural breakthroughs
1
a
: a sudden advance especially in knowledge or technique
a medical breakthrough
b
: a person's first notable success
often used before another noun
a breakthrough novel
the actress's breakthrough performance
2
a
: an act or instance of moving through or beyond an obstacle
a breakthrough in the talks between the region's leaders
a breakthrough agreement
b
: an instance of passing through a barrier or protection
The ice under the surface begins to deteriorate, increasing the risk of breakthroughs.Vicki Winger
specifically, medical : infection occurring in someone who is fully vaccinated against an infectious agent
A vaccine breakthrough occurs when a person tests positive for COVID-19 two weeks after being fully vaccinated against the disease … David Rasbach
often used before another noun
Two other CDC studies of breakthrough cases at nursing homes showed the vaccines protected residents, even when the virus spread through the homes. Maura Dolan
… the academy recently recommended that children receive two doses of the chicken pox vaccine, rather than just one, because the additional dose bolsters immunity and may help reduce breakthrough infection. Maria Raven
3
warfare : an offensive military assault that penetrates and carries beyond a defensive line

break through

2 of 2

verb

broke through; broken through; breaking through; breaks through

intransitive verb

: to make a breakthrough

Examples of breakthrough in a Sentence

Noun Researchers say they have made a major breakthrough in cancer treatment. The police have announced a breakthrough in the murder case. This job could be the breakthrough she's been waiting for.
Recent Examples on the Web
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Noun
However, these breakthroughs come with complex environmental, social and governance (ESG) implications that cannot be overlooked. Deepa Nagraj, Forbes.com, 7 July 2025 Creative breakthroughs are on the horizon, Aquarius. Valerie Mesa, People.com, 7 July 2025
Verb
Reflecting on Run, WSN’s concept to connect buyers with emerging designers in a showroom and runway space held during fashion week in March, Maus acknowledged the challenges of breaking through in the current market. Rhonda Richford, Footwear News, 4 July 2025 When the duo broke through in 2009, American and North American style dubstep was beginning its moment of ubiquity, as artists like Skrillex and Excison delivered sharp, heavy iterations of the U.K.-born sound and countless DJs became a drop jockeys trying to out-pummel the last. Katie Bain, Billboard, 3 July 2025 See All Example Sentences for breakthrough

Word History

First Known Use

Noun

1915, in the meaning defined at sense 3

Verb

1946, in the meaning defined above

Time Traveler
The first known use of breakthrough was in 1915

Browse Nearby Words

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Cite this Entry

“Breakthrough.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/breakthrough. Accessed 11 Jul. 2025.

Kids Definition

breakthrough

noun
break·​through ˈbrāk-ˌthrü How to pronounce breakthrough (audio)
: a sudden advance in knowledge or technique
a breakthrough in medical science

Medical Definition

breakthrough

noun
break·​through ˈbrāk-ˌthrü How to pronounce breakthrough (audio)
: infection occurring in someone who is fully vaccinated against an infectious agent
often used before another noun
breakthrough infections

More from Merriam-Webster on breakthrough

Last Updated: - Updated example sentences
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