galactosePronunciation: /gəˈlaktəʊz, -s/Definition of galactose noun [mass noun] Chemistry a sugar of the hexose class which is a constituent of lactose and many polysaccharides. Origin: mid 19th century: from Greek gala, galaktos 'milk' + -ose2galactose in other Oxford dictionaries Definition of galactose in the US English dictionary
