'arroyo' originates from Spanish, specifically the word 'arroyo', where the form referred to a small stream or brook.

'arroyo' changed from Old Spanish forms such as 'arroio' to modern Spanish 'arroyo', and the word was adopted into English (especially in the American Southwest) with the same form and meaning.

Initially it meant 'small stream' in Spanish; over time, in English it came to be used particularly for seasonal or dry streambeds in arid regions (a more regionally specific usage).