quantum: Meaning and Definition of

quan•tum

1. quantity or amount: the least quantum of evidence.
2. a particular amount.
3. a share or portion.
4. a large quantity; bulk.
1. the smallest quantity of radiant energy, equal to Planck's constant times the frequency of the associated radiation.
2. the fundamental unit of a quantized physical magnitude, as angular momentum.

1. sudden and significant: a quantum increase in productivity.