quantum

1 of 2

noun

quan·​tum ˈkwän-təm 

plural quanta ˈkwän-tə 

1

a

: quantity, amount

b

: portion, part

c

: gross quantity : bulk

2

a

: 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)

quantum

2 of 2

adjective

1

: large, significant

a quantum improvement

2

: of, relating to, or employing the principles of quantum mechanics

quantum physics

Synonyms

Noun

• amount
• measure
• quantity
• volume

Examples of quantum in a Sentence

Noun

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

Despite these challenges, the quantum computing industry has achieved notable milestones. —Trefis Team, Forbes.com, 4 June 2025

Its implications are cosmic, but the quantum realm is definitively a human one. —Andrea Gawrylewski, Scientific American, 3 June 2025

Adjective

This quantum superposition enables these systems to perform complex calculations and process vast datasets by exploring numerous potential outcomes concurrently. —Trefis Team, Forbes.com, 4 June 2025

The agency faces a lethal 57 percent reduction to its $9-billion budget, with deep cuts to every program except those in President Trump’s priority areas, which include artificial intelligence and quantum information science. —Nadia Drake, Scientific American, 3 June 2025

Word History

Etymology

Noun

Latin, neuter of quantus how much

First Known Use

Noun

1567, in the meaning defined at sense 1a

Adjective

1942, in the meaning defined at sense 1

Phrases Containing quantum

• light quantum
• magnetic quantum number
• quantum chromodynamics
• quantum computer
• quantum dot
• quantum electrodynamics
• quantum entanglement
• quantum field theory
• quantum jump
• quantum leap
• quantum mechanics
• quantum number
• quantum theory

Rhymes for quantum

• contemn
• infantum

Kids Definition

quantum

1 of 2 noun

quan·​tum ˈkwänt-əm 

plural quanta ˈkwänt-ə 

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

quantum

2 of 2 adjective

: of or relating to the principles of quantum theory

quantum physics

Medical Definition

quantum

noun

quan·​tum ˈkwänt-əm 

plural quanta ˈkwänt-ə 

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