quantum
Quantum (noun) means the smallest discrete amount of something, especially a fixed unit of energy in physics. Example: “A photon is a quantum of light.”
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).
"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.
Fill the gap
Can you complete this real example?
A photon is a _____ of light.
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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