thermonuclear /-no̅o̅′klē·ər/ [Gk, thermē, heat; L, nucleus, nut kernel] , pertaining to a reaction in which isotopes of hydrogen (protium, deuterium, or tritium) can be fused at temperatures of nearly 100,000,000° C into heavier nuclei of helium atoms. The process is the source of energy of the sun and is used in the explosion of thermonuclear weapons.
