ossein Syllabification: (os·se·in)Pronunciation: /ˈäsē-in/Definition of ossein noun Biochemistry the collagen of bones, used for glues and gelatin, derived by dissolving the mineral content in an acid solution. Origin: mid 19th century: from Latin osseus 'bony' + -in1ossein in other Oxford dictionaries Definition of ossein in the British & World English dictionary