An everglade is a large, slow-moving river of shallow water flowing through a landscape of tall grasses. The most famous example is Florida's Everglades, which looks nothing like what most people imagine when they hear the word “river.” Instead of water rushing between banks, an everglade spreads across miles of flat land, moving so slowly you can barely tell it's flowing at all. The water might only be a few inches deep, and sawgrass (a tall, sharp-edged grass) grows right up through it, creating what looks like an endless golden-green prairie.

The water in an everglade comes from rain and overflowing lakes, then creeps southward toward the ocean over weeks or months. This creates a unique ecosystem where wading birds like herons and egrets hunt for fish, alligators lurk in deeper channels, and trees grow on small islands called hammocks that rise just slightly above the water.

While Florida's Everglades is the most well-known, the term can describe similar wetland landscapes elsewhere, though it's rarely used for anything other than the Florida ecosystem that made the word famous.