-sterone formative element in the names of some steroids, as in androsterone, progesterone. [ad. G. -steron, f.ster(ol sterol + ket)on ketone. App. first used in G. androsteron (Zeitschr.f. phys. Chem. (1934) CCXXIX. 167) and luteosteron (Ber. d. Deut.Chem. Ges. (1934) LXVII. 1271).]