Meaning of QUANTUM in English

n. (pl. quanta)

1. Physics a a discrete quantity of energy proportional in magnitude to the frequency of radiation it represents. b an analogous discrete amount of any other physical quantity.

2 a a required or allowed amount. b a share or portion.

Phrases and idioms:

quantum jump (or leap)

1. a sudden large increase or advance.

2 Physics an abrupt transition in an atom or molecule from one quantum state to another. quantum mechanics (or theory) Physics a system or theory using the assumption that energy exists in discrete units.

Etymology: L, neut. of quantus how much

Oxford English vocab.      Оксфордский английский словарь.