Quantum/ˈkwɑːntəm/ Definition 1 of 5Pro Tip 1/3Small but Mighty In physics, 'quantum' suggests something extremely small yet fundamentally crucial. Atoms are composed of quanta. Pro Tip 2/3Discrete Units 'Quantum' refers to fixed, distinct levels or amounts in scientific contexts, not continuous. Electron transitions happen in quantum steps. Pro Tip 3/3Technical Term Used mainly in technical or scientific fields, not regular conversation. Quantum computing will revolutionize technology.