Correct spelling for the English word "larosan" is [lˈaɹɒsən], [lˈaɹɒsən], [l_ˈa_ɹ_ɒ_s_ə_n] (IPA phonetic alphabet).
Trade name of a soluble compound of casein and calcium oxide (2.5 per cent.), employed in solution in milk in cases of digestive and nutritional disturbances in children.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.