quantum

/ˈkwɑntəm/

/ˈkwɒntəm/

Other forms: quanta

While quantum refers to a general quantity or size, it is most often used in physics as a measure of the smallest amount of something — usually energy — that something can possess. The plural form is quanta.

In the 17th century, the word quantum, from the Latin word for "how much," referred to a portion. Quantum is usually a noun referring to a specific amount of something. However, it can also be used as an adjective, as in the phrase "quantum leap," where it refers to a sudden, important change. Outside of physics, the word might be used with "not" to refer to something insignificant, as in "There's not a quantum of truth in what you say."

Definitions of quantum

1. noun

   (physics) the smallest discrete quantity of some physical property that a system can possess (according to quantum theory)
   types:

   quasiparticle

   a quantum of energy (in a crystal lattice or other system) that has position and momentum and can in some respects be regarded as a particle

   type of:

   amount, measure, quantity

   how much there is or how many there are of something that you can quantify
2. noun

   a discrete amount of something that is analogous to the quantities in quantum theory
   type of:

   quantity

   the concept that something has a magnitude and can be represented in mathematical expressions by a constant or a variable