Obi

Obi, a river and, with its tributaries, great water highway of West Siberia, which rises in the Altai Mountains, and after a course of 2120 m. falls into the Arctic Ocean.

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

Oberon * Objective
Oakum
Oases
Oates, Titus
Obadiah
Oban
Obeid
Obelisk
Ober-Ammergau
Oberlin, Jean Friedrich
Oberon
Obi
Objective
Oblates
Oboe
Obelus
O'Brien, William
O'Brien, William Smith
Obscurantist
Obsidian
Occam
Occasionalism