galactosaminePronunciation: /ˌgalakˈtəʊsəmiːn/Definition of galactosamine noun Biochemistry a crystalline amino sugar, of which chondroitin is a derivative. Chemical formula: C6H13NO5 Origin: early 20th century: from galactose + aminegalactosamine in other Oxford dictionaries Definition of galactosamine in the US English dictionary