noun
Common
quantum
KWON-tuhm
Quantum (noun) means the smallest discrete amount of something, especially a fixed unit of energy in physics. Example: “Each quantum of energy is released in a tiny, fixed packet.”
noun
1
The smallest discrete amount of something, especially a fixed unit of energy in physics.
"Each quantum of energy is released in a tiny, fixed packet."
"A photon is a quantum of light."
"Energy at this scale moves in quanta, not smooth increments."
adj
1
Involving quantum mechanics — the physics of matter and energy at the atomic and subatomic scale.
"She is studying quantum physics at university this year."
"Quantum computers use particles that can exist in more than one state at once."
"The professor's research focuses on quantum theory."
2
Sudden and dramatic rather than gradual — used loosely for a major leap forward.
"The new phone camera is a quantum improvement over the old model."
"The new engine was a quantum leap in efficiency."
"Her career took a quantum jump after the promotion."
How to use quantum
Learner’s notesIn plain EnglishA fixed, indivisible unit — in everyday use, often shorthand for "a huge, sudden jump" (a quantum leap).
Common mistake
"Quantum leap" is popularly used to mean a huge change, but in physics a quantum jump is actually the smallest possible change — the opposite of huge.
Common pairings
quantum leap
quantum mechanics
quantum computer
quantum physics
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Each _____ of energy is released in a tiny, fixed packet.
Etymology
From Latin quantum, "how much" — the neuter form of quantus.
Related words
Frequently asked questions
What does “quantum” mean?
The word “quantum” means the smallest discrete amount of something, especially a fixed unit of energy in physics. In plain terms, a fixed, indivisible unit — in everyday use, often shorthand for "a huge, sudden jump" (a quantum leap).
How do you pronounce “quantum”?
“Quantum” is pronounced KWON-tuhm (/ˈkwɑntəm/ in IPA).
How do you use “quantum” in a sentence?
Here is “quantum” used in a sentence: “A photon is a quantum of light.”
What part of speech is “quantum”?
Depending on how it is used, “quantum” can be a noun and an adjective.
Where does the word “quantum” come from?
The word “quantum” comes from Latin. From Latin quantum, "how much" — the neuter form of quantus.
Is “quantum” a common word?
“Quantum” is a fairly common word in modern English.
How many meanings does “quantum” have?
“Quantum” has 3 distinct senses listed in this dictionary. The most common is: the smallest discrete amount of something, especially a fixed unit of energy in physics.
What is the plural of quantum?
The plural of quantum is quanta, following the Latin pattern, as in 'light is absorbed in discrete quanta.' 'Quantums' is nonstandard and best avoided in careful writing.
What is the difference between quantum and quantity?
A quantity is any amount that can be measured or counted. A quantum is a discrete, fixed amount — especially the smallest possible unit of something, such as a quantum of energy in physics. All quanta are quantities, but quantity carries no sense of an indivisible unit.
Does quantum mean something small or something big?
In physics, a quantum is the smallest discrete amount of something, so strictly it refers to the tiniest possible unit. In everyday use, however, the word often signals size and drama — a 'quantum leap' or 'quantum shift' is a sudden, major change. Context tells you which sense is in play.
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