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 of quantum

Noun

• amount
• quantity

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

Netanyahu told a Cabinet meeting on Sunday that economic and security issues will be high on the leaders’ agenda, as will sharing technology, including artificial intelligence and quantum computing. —ABC News, 25 Feb. 2026

The firm invests in sectors like quantum, space, energy and infrastructure for artificial intelligence. —Max Scheinblum, Denver Post, 24 Feb. 2026

Adjective

The country has funnelled just short of $18 billion in public investment in quantum technology, followed closely by the EU, according to the European Centre for International Political Economy (ECIPE), a think tank. —Kai Nicol-Schwarz, CNBC, 23 Feb. 2026

The teleportation part used a wavelength of 795 nanometers, which is essential for platforms like neutral-atom quantum computers, atomic clocks, and quantum sensors. —Georgina Jedikovska, Interesting Engineering, 23 Feb. 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

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