quantum
n. countablen. the smallest possible amount of energy that can exist. In general use, it describes things that happen in tiny, separate steps rather than a smooth flow.
n. the minimum amount of any physical entity involved in an interaction; a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents.
A photon is a single quantum of light.
In physics, energy is not a continuous stream but is instead released in a specific quantum.
The transition from classical mechanics to a quantum framework required scientists to accept that energy exists in discrete packets rather than as a continuous variable.
From Late Latin quantum, noun use of neuter form of Latin quantus (“how much”).
The plural form is 'quanta'. In legal contexts, it refers to a required or allowed amount, such as 'the quantum of damages'.