hexosePronunciation: /ˈhɛksəʊz, -s/Definition of hexose noun Chemistry any of the class of simple sugars whose molecules contain six carbon atoms, such as glucose and fructose. They generally have the chemical formula C6H12O6. Origin: late 19th century: from hexa- 'six' + -ose2hexose in other Oxford dictionaries Definition of hexose in the US English dictionary