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

The quantum vacuum, or the properties of empty space, is something that can be measured in various ways. —Big Think, 24 Mar. 2026

This requirement is why quantum labs mostly comprise advanced cooling technologies. —Etiido Uko march 23, New Atlas, 23 Mar. 2026

Adjective

In addition, the find opens the door for designing quantum materials. —Georgina Jedikovska, Interesting Engineering, 25 Mar. 2026

The difference in what the vacuum state is in different regions of space — particularly in the presence of a horizon, whether a cosmological or an event horizon — leads to the production of radiation and particle-antiparticle pairs wherever quantum fields are present. —Big Think, 24 Mar. 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