quantum

noun (plural quanta /-tə/)

• 1 Physics a discrete quantity of energy proportional in magnitude to the frequency of the radiation it represents.
• an analogous discrete amount of any other physical quantity, such as momentum or electric charge.
• Physiology the unit quantity of acetylcholine released at a neuromuscular junction by a single synaptic vesicle, contributing a discrete small voltage to the measured end-plate potential.

• 2a required or allowed amount, especially an amount of money legally payable in damages.
• a share or portion:each man has only a quantum of compassion