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
• 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 team believes the findings represent the beginning of a new chapter in quantum simulation by transforming quantum computers into labs to explore the vast, uncharted world of out-of-equilibrium quantum matter. —Georgina Jedikovska, Interesting Engineering, 11 Sep. 2025

Rather than incrementally improving classical AI, quantum represents a leap—offering broad, simultaneous visibility into datasets and potentially enabling diagnosis long before symptoms appear. —Somnath Banerjee, Forbes.com, 11 Sep. 2025

Adjective

The state is a non-equilibrium quantum state of matter in a system driven by a time-periodic Hamiltonian, which is a physical system whose governing rules change over time, but with a repeating, predictable cycle. —Georgina Jedikovska, Interesting Engineering, 11 Sep. 2025

In theory, certain quantum algorithms could shrink model training times from weeks to hours by evaluating many model parameters at once, rather than an iterative trial-and-error approach. —Somnath Banerjee, Forbes.com, 11 Sep. 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