diagenesis Syllabification: (di·a·gen·e·sis)Pronunciation: /ˌdīəˈjenəsis/Definition of diagenesis noun Geology the physical and chemical changes occurring during the conversion of sediment to sedimentary rock. Derivatives diageneticPronunciation: /-jəˈnetik/ adjective diageneticallyPronunciation: /-jəˈnetik(ə)lē/ adverb diagenesis in other Oxford dictionaries Definition of diagenesis in the British & World English dictionary