quantum

1 of 2

noun

quan·tum ˈkwän-təm pluralquanta ˈkwän-tə Synonyms of quantumSimple DefinitionA Simple Definition is available from our Learner's Dictionary to help you understand the meaning faster.1a: quantity, amountb: portion, partc: gross quantity : bulk2a: any of the very small increments or parcels into which many forms of energy are subdividedb: any of the small subdivisions of a quantized physical magnitude (such as magnetic moment; i love you)

quantum

2 of 2

adjective

1: large, significanta quantum improvement2: of, relating to, or employing the principles of quantum mechanicsquantum physics

Synonyms of quantum

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Noun

Examples of quantum in a Sentence

Nounthe sum of human knowledge is now so immense that even a highly educated person can hope to absorb only a tiny quantum of itRecent Examples on the WebExamples are automatically compiled from online sources to show current usage. Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback.NounThe paper also provides forecasts (based on the IBM quantum computing roadmap) on the rate of current advancements and the timeline of maturity of these computational solutions.—Aditya Jadhav, Interesting Engineering, 28 May 2026True quantum-safe migration will depend on the deployment of post-quantum address formats like P2QRH, which are currently in the draft BIP stage and not yet activated on mainnet.—Sandy Peng, Forbes.com, 28 May 2026AdjectiveThe researchers said even quantum random number generators based on photons and beam splitters are not fully free from systematic errors or bias.—Neetika Walter, Interesting Engineering, 27 May 2026The general idea of using a quantum network to improve optical interferometry has been around for decades, but the challenge has been making one robust enough to receive and process these incoming photons.—K. R. Callaway, Scientific American, 27 May 2026

Word History

Etymology

Noun

Latin, neuter of quantus how much

First Known Use

Noun

1567, in the meaning defined at sense 1a

Adjective

1924, in the meaning defined at sense 2

Time TravelerThe first known use of quantum was in 1567See more words from the same year

Phrases Containing quantum

Rhymes for quantum

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quantongquantumquantum chromodynamics

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Good vocabulary, Mr. Bond.

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“Quantum.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/quantum. Accessed 1 Jun. 2026.

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Kids Definition

quantum

1 of 2nounquan·tum ˈkwänt-əm pluralquanta ˈkwänt-ə : the smallest amount of many forms of energy (as light)

quantum

2 of 2adjective: of or relating to the principles of quantum theoryquantum physics

Medical Definition

quantum

nounquan·tum ˈkwänt-əm pluralquanta ˈkwänt-ə 1: one of the very small increments or parcels into which many forms of energy are subdivideda molecule of rhodopsin in the human eye can cause a response to a single quantum of light2: 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