>bos is a MALE cow, vacca a FEMALE one

no bull?
But seriously, this is all kind of odd. the major sense of cow in English is "the female of any bovine animal (as the ox, bison, or buffalo); most commonly applied to the female of the domestic species (Bos Taurus)". Bull is most commonly applied to the male of Bos Taurus. cow and bull are also used in the same manner for other large animals (elephant, whale, etc.) In the U.S. cow is used for either sex of Bos Taurus (and the plural is cattle); and, interestingly, 'bossy' is dialect for cow (female) and toro is the Spanish word for bull. ole!