A wildebeest is a large wild animal of Africa, a kind of antelope, with a heavy head, curved horns, a beard of hair under the neck, a mane along the back of the neck, and a long thin tail. It looks a little like a cow at the front and a horse at the back, which is why people notice it. It eats grass and lives on the open plains of eastern and southern Africa.

Wildebeest are most famous for moving together. More than a million of them travel in one huge group across Tanzania and Kenya every year, following the rain and the new grass, crossing rivers full of crocodiles. This is what people mean by "the great migration", and it is the picture most English speakers have when they hear the word.

The plural is unusual. Both "wildebeest" and "wildebeests" are correct, but people who talk about them a lot — guides, nature programmes — normally say "wildebeest" for both one and many: "we saw thousands of wildebeest." That works like "sheep" and "deer".

The animal has a second English name, gnu, said "noo" (the g is silent). Gnu and wildebeest mean the same animal. Wildebeest is the ordinary word today; gnu turns up in crossword puzzles and old books.