quantum UK /ˈkwɒntəm/US /ˈkwɑntəm/noun 10adjective 4forms 2phrases 1 noun10 •The total amount of something; quantity.The reader will perhaps be curious to know the quantum of this present, but we cannot satisfy his curiosity. — 1749 •The smallest possible, and therefore indivisible, unit of a given quantity or quantifiable phenomenon.The quantum of light energy was later called a photon. — 2002 •The amount of compensation awarded to a successful party in a lawsuit. •The length or magnitude of the sentence handed down to someone who has been found guilty of a crime. •The amount or quantity observably present, or available.Each man has only a quantum of compassion, he argued, and mine is used up for the day. — 1979 •Amount of goods produced or demanded. •Ellipsis of quantum computing.Developing for quantum has never been more accessible. •The amount of time allocated for a thread to perform its work in a multithreaded environment. •The minimum dose of a pathogen required to cause an infection. •A definite portion of a manifoldness, limited by a mark or by a boundary.Defined parts of a manifoldness are called Quanta — 1882 adjective4 •Involving quanta, quantum mechanics or other aspects of quantum physics. •Relating to a quantum computer. •(informal) Of a change, significant. •Of a change, sudden or discrete, without intermediate stages. formsquanta · quantums Phrases with quantum quantum tunnelTo undergo the process of quantum tunnelling.