Dictionary of Ichthyology  

wadi (plural widyan but usually wadis in English) = Arabic for a watercourse, usually dry except during the rainy season and sometimes permanently dry but some have flowing water or pools and fish.

Guadalquivir River at Cordoba, Spain, 26 October 2012. From the Arabic al-wādi al-kabīr (الوادي الكبير) meaning "The Great River". Photograph by Brian W. Coad.

Canadian Museum of Nature
www.briancoad.com