A deer is a four-legged, hoofed animal with antlers. Disney’s Bambi is a famous deer. There are deer all over the world, but American deer are light brown, and are often found nibbling on plants at dusk.
The main thing that distinguishes deer from other horned animals, like antelope, is that deer shed their antlers once a year and grow new ones. A female deer, called a "doe," has smaller antlers than the male, or "buck." The Old English root of deer, deor, means "beast" or "animal," and was originally used generally to refer to all four-legged wild animals.