ecdysone Syllabification: (ec·dy·sone)Pronunciation: /ˈekdiˌsōn/Definition of ecdysone noun Biochemistry a steroid hormone that controls molting in insects and other arthropods. Origin: 1950s: from Greek ekdusis 'shedding' + -oneecdysone in other Oxford dictionaries Definition of ecdysone in the British & World English dictionary