quantum

American  

[kwon-tuhm] / ˈkwɒn təm /

noun

• quanta
  plural

1. quantity or amount.

   the least quantum of evidence.

2. a particular amount.

3. a share or portion.

4. a large quantity; bulk.

5. Physics.

   1. the smallest quantity of radiant energy, equal to Planck's constant times the frequency of the associated radiation.

   2. the fundamental unit of a quantized physical magnitude, as angular momentum.

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adjective

1. sudden and significant.

   a quantum increase in productivity.

quantum British  

/ ˈkwɒntəm /

noun

1. physics

   1. the smallest quantity of some physical property, such as energy, that a system can possess according to the quantum theory

   2. a particle with such a unit of energy

2. amount or quantity, esp a specific amount

3. (often used with a negative) the least possible amount that can suffice

   there is not a quantum of evidence for your accusation

4. something that can be quantified or measured

5. (modifier) loosely, sudden, spectacular, or vitally important

   a quantum improvement

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quantum Scientific  

/ kwŏn′təm /

• quanta
  plural

1. A discrete, indivisible manifestation of a physical property, such as a force or angular momentum. Some quanta take the form of elementary particles; for example, the quantum of electromagnetic radiation is the photon, while the quanta of the weak force are the W and Z particles.

2. See also quantum state

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Other Word Forms

Derived Forms

• quantumness
  noun

Inflected Forms

Nouns

• quanta
  plural

Etymology

Origin of quantum

1610–20; noun use of neuter of Latin quantus how much

Explanation

While quantum refers to a general quantity or size, it is most often used in physics as a measure of the smallest amount of something — usually energy — that something can possess. The plural form is quanta. In the 17th century, the word quantum, from the Latin word for "how much," referred to a portion. Quantum is usually a noun referring to a specific amount of something. However, it can also be used as an adjective, as in the phrase "quantum leap," where it refers to a sudden, important change. Outside of physics, the word might be used with "not" to refer to something insignificant, as in "There's not a quantum of truth in what you say."

Example Sentences

See Examples For:

quantum quanta

The researchers expect that as future experiments become larger and more complicated, however, quantum computers will eventually be able to solve versions of these problems that classical machines cannot handle.

From Science Daily ● Sep. 26, 2026

Microsoft and Amazon are expanding their footprint in quantum computing, even as a commercial breakout remains years away.

From Barron's ● Sep. 25, 2026

In May, tiny, unprofitable Astrotech, which touts “Moon-based semiconductor and quantum computing applications,” soared as much as 2,600% on 9,000 times its typical trading volume.

From The Wall Street Journal ● Sep. 25, 2026

One of the major puzzles in fundamental physics involves the enormous difference between the scale of the universe we experience and the Planck scale, the fundamental energy scale associated with quantum gravity.

From Science Daily ● Sep. 23, 2026

Modern quantum mechanics combines both ideas, and it is customary today to think of light as behaving in some circumstances as a beam of particles and in others as a wave.

From "Cosmos" by Carl Sagan

At wide-open throttle, the raunchiness doesn’t come in wild quanta but in one smoothly linear, incredibly steep exponential function, with no interval for tactility and feedback.

From The Wall Street Journal ● Oct. 30, 2025

This process allows the penetration and pinning of magnetic flux quanta, which in turn creates a magnetic stray field.

From Science Daily ● Apr. 17, 2024

Quantum theory typically deals with the universe in tiny chunks, or quanta, while general relativity takes the cosmos to be continuous even at the smallest scales.

From Scientific American ● Aug. 19, 2023

Quantum mechanics describes how, in the subatomic realm, everything is broken up in discrete chunks, or quanta, such as the individual particles of light called photons.

From New York Times ● May 8, 2023

Albert Einstein, a twenty-six-year-old patent clerk, showed the physics world that nature worked in quanta rather than in smooth increments.

From "Zero: The Biography of a Dangerous Idea" by Charles Seife