quan·​tum | \ ˈkwän-təm How to pronounce quantum (audio) \
plural quanta\ ˈkwän-​tə How to pronounce quanta (audio) \

Definition of quantum

 (Entry 1 of 2)

b : portion, part
c : gross quantity : bulk
2a : any of the very small increments or parcels into which many forms of energy are subdivided
b : any of the small subdivisions of a quantized physical magnitude (such as magnetic moment)



Definition of quantum (Entry 2 of 2)

1 : large, significant a quantum improvement
2 : of, relating to, or employing the principles of quantum mechanics quantum physics

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Synonyms for quantum

Synonyms: Noun

amount, measure, quantity, volume

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Examples of quantum in a Sentence


the sum of human knowledge is now so immense that even a highly educated person can hope to absorb only a tiny quantum of it

Recent Examples on the Web: Noun

Alice measures the state of her friend and her lab, treating all of it as one quantum system, and uses quantum theory to make predictions. Wired, "A New Quantum Paradox Flags Errors in Our View of Reality," 9 Dec. 2018 Vern Brownell, the boss of D-Wave, which calls itself the world’s leading quantum-computing firm, says that just 0.25% of its revenue comes from Canadian customers. The Economist, "EconomyRedistribution and innovation drive Canada’s changing economy," 25 July 2019 But solving such problems would require 100,000 qubits and the means to correct errors in the delicate quantum waves. Adrian Cho, Science | AAAS, "How to evaluate computers that don’t quite exist," 26 June 2019 We might be tempted to think of electrons as resembling planets orbiting a star; instead their wavy quantum nature gives rise to shapes that Mr. James likens to dumbbells or balloons. Andrew Crumey, WSJ, "‘Mendeleyev’s Dream’ and ‘Elemental’ Review: Cracking the Chemical Code," 21 June 2019 Supercomputing is one of the key technologies of the future that China is seeking to dominate, in addition to artificial intelligence and quantum computing. Paul Mozur, New York Times, "U.S. Blacklists More Chinese Tech Companies Over National Security Concerns," 21 June 2019 While companies are investing heavily in the technology, no scalable, commercial-grade quantum computer has been built yet. Sara Castellanos, WSJ, "When Quantum Computing Meets AI: Smarter Digital Assistants and More," 23 May 2019 When a quantum computer executes an action, in every computer cycle there is some probability that a qubit will get corrupted. Quanta Magazine, "The Argument Against Quantum Computers," 7 Feb. 2018 The year is 2019, and the brainy engineers of Silicon Valley are hunkered down, working on transformative, next-generation technologies like self-driving cars, digital currencies and quantum computing. Kevin Roose, New York Times, "Would You Pay $30 a Month to Check Your Email?," 27 June 2019

Recent Examples on the Web: Adjective

The discovery of supergravity was the beginning of including quantum variables in describing the dynamics of spacetime. Martin Finucane, BostonGlobe.com, "MIT emeritus professor wins $1m for particle physics work," 6 Aug. 2019 The fabric of space and time is widely believed by physicists to be emergent, stitched out of quantum threads according to an unknown pattern. Wired, "Is the Universe a Hologram? Maybe! This Math Trick Shows How," 24 Feb. 2019 As cool as that sounds, ghost imaging isn't necessarily quantum. Chris Lee, Ars Technica, "Humans can perform ghost imaging, no computer required," 4 Sep. 2018 His bookshelf was lined with volumes on Hindu philosophy and quantum physics—his favourite subjects. Vikram Zutshi, Quartz India, "Why do abusive men (and the women who support them) behave the way they do?," 19 July 2019 Producers of complex products like airplanes or electronics would be among the biggest potential users of Dust’s technology, which emerged from Dust CEO Orin Gaathon’s research into the quantum properties of diamonds at MIT. David Z. Morris, Fortune, "Dust Identity Raises $10 Million to Secure the Global Supply Chain—Using Diamonds," 17 July 2019 And that includes two world wars, the development of Einstein's theory of relativity, quantum physics and nuclear weapons. William Harwood, CBS News, "50 years later, Apollo 11's "one giant leap" remains a defining moment in human history," 14 July 2019 Planck's constant, named for physicist Max Planck, is a key quantity in quantum physics. Ashley Strickland, CNN, "Scientists noticed an error in the new season of 'Stranger Things'," 11 July 2019 The latest batch, being auctioned off by Christie's, gives further insight into Einstein's thoughts on quantum physics, including his criticism for other scientists for their lack of understanding of the topic. Fox News, "God 'does not play dice with the universe,' Einstein writes in letter up for auction," 12 June 2019

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'quantum.' 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 quantum


1567, in the meaning defined at sense 1a


1942, in the meaning defined at sense 1

History and Etymology for quantum


Latin, neuter of quantus how much

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Statistics for quantum

Last Updated

14 Aug 2019

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Time Traveler for quantum

The first known use of quantum was in 1567

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English Language Learners Definition of quantum

 (Entry 1 of 2)

physics : the smallest amount of many forms of energy (such as light)



English Language Learners Definition of quantum (Entry 2 of 2)

physics : of, relating to, or using the principles of quantum theory


quan·​tum | \ ˈkwänt-əm How to pronounce quantum (audio) \
plural quanta\ ˈkwänt-​ə How to pronounce quanta (audio) \

Medical Definition of quantum

1 : one of the very small increments or parcels into which many forms of energy are subdivided a molecule of rhodopsin in the human eye can cause a response to a single quantum of light
2 : one of the small molecular packets of a neurotransmitter (as acetylcholine) released into the synaptic cleft in the transmission of a nerve impulse across a synapse

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Comments on quantum

What made you want to look up quantum? Please tell us where you read or heard it (including the quote, if possible).


a usually brief trip or an expedition

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