The noun (and adjective) bovine, from the Latin term bos by way of the French word bovin, is the scientific word for cattle and related animals; it is one of several words in various languages that is cognate with cow, as both words apparently stem from a proto-Indo-European word imitative of mooing. (In allusion to the unintelligent, slow-moving characteristics of cattle, it is also applied to slow, stupid human behavior.)
From bovine we also get beef (from Old French buef), which usually refers in general usage to the meat of cattle used as food, but it also applies to adult cattle; the plural beefs has overtaken the original beeves. Use of the word beef has extended to the idea of “complaint” (perhaps based on the griping of military personnel about their beef rations) and to the notions of brawniness (the adjective beefy) and adding strength (the idiom “beefing up”).
Beefsteak refers to a particular cut of beef, and Beefeater is another designation for the Yeoman Warders, traditional guards of the Tower of London, which originated as a nickname alluding to the rations of beef and beef broth they consumed.
Bull, from the Old English word bula, refers to male specimens of cattle (especially those not deprived of reproductive capability) and other large mammals. A bullock is a young or castrated bull. By extension, bull describes a brawny man (and was slang for a police officer) or a person who buys stocks because he or she expects the price to rise or hopes for a rise to occur; to bull is to act forcefully or violently, and the word is the first element of a compound referring obliquely to excrement and describing speech that is boastful, foolish, or misleading.
Cattle itself is ultimately from the Medieval Latin noun capitale, meaning “property” or “stock,” by way of the Old French term chattel; it is cognate with capital in the sense of “assets” or “stock” and with chattel, meaning “property.”
Cow, which technically describes adult females of various large animal species, including cattle, but is used popularly to refer to cattle of either gender, stems from Old English but, as mentioned earlier, is cognate with a variety of words from other languages that pertain to cattle.
Ox (the word is from the Old English oxa) refers to male cattle bred as work animals (usually draft animals, meaning that they pull wagons or other vehicles) rather than as a source of beef; the plural is oxen. A steer is a young bull or ox, though in American English usage it designates any male beef cattle; the word comes from the Old English term steor, meaning “bull.”
Two other terms associated with cattle are calf (plural calves), from the Old English word cealf, meaning “young cow” (of either gender), and heifer, from the Old English word heahfore, which refers to a young (female) cow, especially one that has not yet borne a calf. The verb calve refers not only to giving birth to a calf but also, by extension, to the separation of a small piece of ice from a glacier or other mass. (Calf, in the sense of the fleshy part of the lower leg, may be a distant relative.)
The slang term dogie, used by cowboys but of unknown origin, refers to an orphaned calf. Speaking of cowboys, the word cowboy, as well as cowhand, cowherd, cowpoke, and cowpuncher (the latter two words derived from the notion of prodding cattle), refers to one who tends cattle. The idea of cowboys as spirited (perhaps inspired by the behavior of cowboy characters in western films and television programs) gave rise in the late twentieth century to the use of cowboy to denote aggression or recklessness. Cowman generally describes a cattle rancher rather than those he employs.