The 188 kilometers long Orge is a right tributary of the river Daugava.

There are three main versions of the etymology of Ogre's name (both town and river).

Whereas Estonian linguist Paul Alvre takes into consideration an older form of the Ogre river's name (Wogene, Woga) first found in Livonian Chronicle of Henry (1180–1227), and argues that it cognates with Estonian word voog (with possible meanings: "stream, flow, waves"), therefore showing connection with Finno-Ugric languages, most probably early Livonian language.

A third etymology gives a reconstructed form *Vingrē, related to Lithuanian vingrùs, "meandering, curly" or Latvian vingrs, "nimble;" thus meaning "the meandering river"; the village of Engure has the same root.

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