1) Atomic 2) Nuclear 1) Nuclear 
Pertaining to nuclear reactions brought about by nuclear fusion; (e.g., the fusion of hydrogen to helium at temperatures of over 100,000,000°C). (the reaction in the 'hydrogen bomb'). ... (05 Mar 2000) ... 
Type: Term Pronunciation: ther′mō-nū′klē-ăr Definitions: 1. Pertaining to nuclear reactions brought about by nuclear fusion (the fusion of hydrogen to helium at temperatures of over 100,000,000°C; the reaction in the 'hydrogen bomb').
[adj] - using nuclear weapons based on fusion as distinguished from fission
thermonuclear 1. Pertaining to nuclear reactions brought about by nuclear fusion; (e.g., the fusion of hydrogen to helium at temperatures of over 100,000,000°C). 2. The reaction in the 'hydrogen bomb'.
adjective using nuclear weapons based on fusion as distinguished from fission