thermonuclear reaction

noun Chemistry, Physics.

1. a nuclear-fusion reaction that takes place between the nuclei of a gas, especially hydrogen, heated to a temperature of several million degrees.

noun

1. a nuclear fusion reaction occurring at a very high temperature: responsible for the energy produced in the sun, nuclear weapons, and fusion reactorsSee nuclear fusion, hydrogen bomb

A reaction between nuclei, usually fusion, which releases very large amounts of energy.