The musk deer of Asia and water chevrotain of tropical African and Asian forests are not usually regarded as true deer and form their own families: Moschidae and Tragulidae, respectively.
The word "deer" was originally broader in meaning, but became more specific over time. In Middle English, der meant a wild animal of any kind. This was as opposed to cattle, which then meant any sort of domestic livestock that was easy to collect and remove from the land, from the idea of personal-property ownership and related to modern chattel and capital. Cognates of Old English dēor in other dead Germanic languages have the general sense of "animal", such as Old High German tior, Old Norse djur or dȳr, Gothic dius, Old Saxon dier, and Old Frisian diar.
This general sense gave way to the modern English sense by the end of the Middle English period, around 1500. However, all modern Germanic languages save English and Scots retain the more general sense: for example, German Tier, Alemannic Diere or Tiere, Pennsylvania Dutch Gedier, Dutch dier, Afrikaans dier, Limburgish diere, Norwegian dyr, Swedish djur, Danish dyr, Icelandic dýr, Faroese dýr, West Frisian dier, and North Frisian diarten, all of which mean "animal". .
For most types of deer in modern English usage, the male is called a "buck" and the female is termed a "doe", but the terms vary with dialect, and especially according to the size of the species. For many larger deer, the male is termed a "stag", while for other larger deer the same words are used as for cattle: "bull" and "cow". The male red deer is a "hart", especially if more than five years old, and the female is a "hind", especially if three or more years old; both terms can also be used for any species of deer, and were widely so used in the past. Terms for young deer vary similarly, with that of most smaller species being called a "fawn" and that of most larger species "calf"; young of the smallest kinds may be a kid. A castrated male deer is a "havier". A group of deer of any kind is a "herd". The adjective of relation pertaining to deer is cervine; like the family name "Cervidae", this is from, "deer".
Venison originally described meat of any game animal killed by hunting, and was applied to any animal from the families Cervidae, Leporidae, and Suidae, and certain species of the genus Capra . In the northern hemisphere, the usage of this term is now almost entirely restricted to the flesh of various species of deer.
In South African English, venison is used to refer to the meat of antelope. There are no native Cervidae in sub-Saharan Africa.
Deer are widely distributed, with indigenous representatives in all continents except Antarctica and Australia, though Africa has only one native deer, the Barbary stag, a subspecies of red deer that is confined to the Atlas Mountains in the northwest of the continent. However, fallow deer have been introduced to South Africa.
Deer live in a variety of biomes, ranging from tundra to the tropical rainforest. While often associated with forests, many deer are ecotone species that live in transitional areas between forests and thickets and prairie and savanna . The majority of large deer species inhabit temperate mixed deciduous forest, mountain mixed coniferous forest, tropical seasonal/dry forest, and savanna habitats around the world. Clearing open areas within forests to some extent may actually benefit deer populations by exposing the understory and allowing the types of grasses, weeds, and herbs to