break·​through | \ ˈbrāk-ˌthrü How to pronounce breakthrough (audio) \
plural breakthroughs

Essential Meaning of breakthrough

1 : a sudden increase in knowledge, understanding, etc. : an important discovery that happens after trying for a long time to understand or explain something Researchers say they have made/achieved a major breakthrough in cancer treatment. a scientific breakthrough The police have announced a breakthrough in the murder case.
2 : a person's first important success This job could be the breakthrough she's been waiting for.

Full Definition of breakthrough

 (Entry 1 of 2)

1a : 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 novelthe actress's breakthrough performance
2a : 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

broke through; broken through; breaking through; breaks through

Definition of break through (Entry 2 of 2)

intransitive verb

: to make a breakthrough

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Synonyms & Antonyms for breakthrough

Synonyms: Noun

Antonyms: Noun

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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.
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Recent Examples on the Web: Noun The study helps explain on a cellular level an observation that public health experts are seeing in the real world -- protection against severe disease is holding strong, even as protection against mild breakthrough infections fluctuates over time. Sony Salzman, ABC News, 15 Oct. 2021 Research has now confirmed that of two groups of people exposed to delta, the cohort that had been vaccinated five months earlier had a more than 50% higher rate of symptomatic breakthrough infections. Yasufumi Saito, Fortune, 13 Oct. 2021 Because Covid case counts remain high in some areas of the US, breakthrough infections and lockdowns continue to disrupt life inside nursing homes. Lila Maclellan, Quartz, 12 Oct. 2021 An Israeli study of 1,497 vaccinated health care workers reported 39 breakthrough infections, and 19 percent of those workers still had symptoms six weeks after their convalescence. Lois K. Solomon,, 11 Oct. 2021 Vaccine breakthrough infections -- which happen when a fully vaccinated person gets infected with Covid-19 -- are a problem for Covid vaccines around the world, including the highly effective mRNA shots developed by Pfizer/BioNtech and Moderna. Jessie Yeung, CNN, 11 Oct. 2021 It’s the unvaccinated people in the group who are at highest risk of getting Covid, but breakthrough infections can happen, especially to those who are medically vulnerable. New York Times, 8 Oct. 2021 But does that mean that, in practice, the drug will only be used in unvaccinated patients, or will it be used in cases of breakthrough infections? Matthew Herper, STAT, 6 Oct. 2021 Other research found that Johnson & Johnson recipients were more likely to have breakthrough infections or symptomatic covid-19 than recipients of the other two vaccines. Compiled Democrat-gazette Staff From Wire Reports, Arkansas Online, 5 Oct. 2021

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'breakthrough.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of breakthrough


1915, in the meaning defined at sense 3


1946, in the meaning defined above

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Time Traveler for breakthrough

Time Traveler

The first known use of breakthrough was in 1915

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Dictionary Entries Near breakthrough

break the truce


break through

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Statistics for breakthrough

Last Updated

21 Oct 2021

Cite this Entry

“Breakthrough.” Dictionary, Merriam-Webster, Accessed 26 Oct. 2021.

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More Definitions for breakthrough


break·​through | \ ˈbrāk-ˌthrü How to pronounce breakthrough (audio) \

Kids Definition of breakthrough

: a sudden advance or successful development a breakthrough in medical research

More from Merriam-Webster on breakthrough

Nglish: Translation of breakthrough for Spanish Speakers

Britannica English: Translation of breakthrough for Arabic Speakers Encyclopedia article about breakthrough


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