A hobby/genre which focuses on artwork and stories about animal-headed people. Unfortunately, the brainless boglumps from anti-furry websites just don't "get" furry fandom and clutter up UrbanDictionary with flimsy crapulence because they're incapable of creating anything of their own.
Let's break it down so there can be no confusion: You don't have to think you're an animal to be a furry fan. You don't have to rave about your inner platypus to be a furry fan. You don't have to insert the word "fur" into every sentence to be a furry fan. You don't have to wear a fursuit to be a furry fan. You don't have to like furry porn to be a furry fan.
Most furries are just folks who thought "The Lion King" or "Teenage Mutant Ninja Turtles" or even Sonic the Hedgehog was majorly cool. They write about and draw cartoon animals. I have no idea why this makes some people go apeshit, but there ya go.
Furry fandom makes the brainless boglumps from CrushYiffDestroy waste their lives away and that's just sad.