lactalbuminPronunciation: /lakˈtalbjʊmɪn/Definition of lactalbumin noun [mass noun] Biochemistry a protein or mixture of similar proteins occurring in milk, obtained after the removal of casein and soluble in a salt solution. Origin: late 19th century: from lacto- 'of milk' + albuminlactalbumin in other Oxford dictionaries Definition of lactalbumin in the US English dictionary