1. (Abbr. R.) A large natural stream of water emptying into an ocean, lake, or other body of water and usually fed along its course by converging tributaries.
2. A stream or abundant flow: a river of tears.

up the river Slang.

1. In or into prison.

[Middle English rivere, from Anglo-Norman, from Vulgar Latin *rīpāria, from Latin, feminine of rīpārius, of a bank, from rīpa, bank.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.