1. subst. A large and often winding stream which drains a land mass, carrying water down from higher areas to a lower point, ending at an ocean or in an inland sea.
Occasionally rivers overflow their banks and cause floods.
2. subst. Any large flow of a liquid in a single body.
a river of blood
3. subst. (poker) The last card dealt in a hand.
4. subst. (typography) A visually undesirable effect of white space running down a page, caused by spaces between words on consecutive lines happening to coincide.
5. v. (poker) To improve one’s hand to beat another player on the final card in a poker game.