A gaucho is a cowboy of the South American grasslands — especially Argentina, Uruguay, and southern Brazil — who lives by the horse, the cattle, and the open plains. English borrowed the word from Spanish and still uses it as a kind of job-and-culture name, not as a casual word for any rider. People say it when they mean that particular South American figure: the wide trousers, the silver knife, the long days on horseback. It is not the same as the cowboy of the United States, though films and books sometimes mix the two pictures together. In English it is a fairly special word: you meet it in history, travel writing, and stories about the pampas, not in everyday talk about work. It can also name the style (gaucho trousers, a gaucho look) when fashion borrows the image.