Horned means having horns: hard, pointed growths that stick out from an animal's head. A horned toad (which is actually a lizard, not a toad) has spiky projections that look like tiny horns. Rhinoceroses, bighorn sheep, and many cattle are horned animals.

Horns are made of bone covered with a tough material called keratin, the same stuff your fingernails are made from. Unlike antlers, which deer shed and regrow each year, horns are permanent. Animals use their horns for defense, for fighting rivals, and sometimes for digging or stripping bark from trees.

The word also appears in descriptions of mythical creatures and costumes. A horned helmet might have decorative horns attached to it (though real Viking helmets probably didn't, despite what movies show). In stories, devils are often depicted as horned.

When you see horned describing something in nature, you're usually learning about an animal's distinctive feature, like the horned viper with its pointed scales above each eye, or the horned owl with its prominent ear tufts (which aren’t actually horns).