nuclear fusion

from the GNU version of the Collaborative International Dictionary of English.

• noun A type of nuclear reaction in which atomic nuclei combine to form more massive nuclei with the simultaneous release of energy.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun physics The combining of the nuclei of small atoms to form the nuclei of larger ones, with a resulting release of large quantities of energy; the process that makes the sun shine, and hydrogen bomb explode.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy