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

Replacing him is longtime Amazon Web Services (AWS) executive Peter DeSantis, who will lead a new organization that drives the development of its AI models, custom computer chips (which include its Graviton, Trainium, and Nitro chips), and quantum computing efforts. —Andrew Nusca, Fortune, 18 Dec. 2025

When a qubit fails, it can no longer be used for running complex calculations, and the loss of this information can induce errors, further complicating the use of quantum computing. —Ameya Paleja, Interesting Engineering, 17 Dec. 2025

Adjective

Among other achievements, Garwin worked with Fermi to build an analog computer to visualize the solutions to the Schrödinger equation, a key equation in quantum physics that defines the motion of particles. —Adam Harrington, CBS News, 18 Dec. 2025

Aided by fellow university chemist Robert Cava, the team used the rare-earth element tantalum to build their quantum circuit. —Ameya Paleja, Interesting Engineering, 17 Dec. 2025

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