Oka

Oka, a river of Central Russia, which rises in Orel and flows N., then E., then N. again, joining the Volga at Nijni-Novgorod after a course of over 700 m., navigable nearly all the way; on its banks are Orel, Kaluga, and Riazan, while Moscow stands on an affluent.

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

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