thermonuclear
adjective /ˌθɜːməʊˈnjuːkliə(r)/
  /ˌθɜːrməʊˈnuːkliər/
- connected with nuclear reactions that only happen at very high temperatures
- a thermonuclear reaction
 
Oxford Collocations DictionaryThermonuclear is used with these nouns:- reaction
 - weapon