Ohio River

Ohio River, formed by the confluence of the Alleghany and the Monongahela, pursues a westward course of 1000 m., separating Ohio, Indiana, and Illinois from West Virginia and Kentucky, and after receiving sundry tributaries joins the Mississippi, being the largest and, next to the Missouri, the longest of its affluents; it is navigable for the whole of its course; on its banks stand Pittsburg, Cincinnati, Louisville, and Madison.

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

Ohio * Ohm, Georg Simon
Offenbach, Jacques
Offertory
Ofterdingen, Heinrich von
Ogham
Oglethorpe, James Edward
Ogowe`
O'Groat's House, John
Ogyges
Ogygia
Ohio
Ohio River
Ohm, Georg Simon
Ohnet, Georges
Oil City
Oka
Oken, Lorenz
Okhotsk, Sea of
Oklahoma
Okuma, Count
Olaf, St.
Olaüs