Chem., combining form of mod.L. ferrōsus FERROUS. Only in ferroso-ferric oxide (see quots.).
1853. R. Hunt, Man. Photography, 55. That peculiar intermediate oxide to which the name of Ferroso-ferric has been given by Berzelius.
1870. J. T. Sprague, in Eng. Mech., 11 March, 621/3. The magnetic property of a natural substance, Ferrosoferric Oxide Fe3O4 or FeO + Fe2O3 known as the loadstone, was discovered in early times from its power of attracting and adhering to iron.
