Orange River

Orange River or Gariep, chief river of South Africa, rises in the eastern highlands of Basutoland, and flows 100 m. westward to the Atlantic, receiving the Vaal and the Caledon as tributaries, and having Cape Colony on the S. bank and the Orange Free State, Griqualand West, Bechuanaland, and German Namaqualand on the N.; a bar at the mouth and the aridity of its lower course make it unfit for navigation.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Oran * Orange River Colony
Ophir
Ophites
Opie, John
Opinicus
Opitz, Martin von
Oporto
Opportunist
Optimism
Opus Operatum
Oran
Orange River
Orange River Colony
Orangemen
Oratorio
Oratory, Congregation of the
Orcagna
Orchardson, William Quiller
Orcus
Ordeal
Ordericus Vitalis
Orders in Council