steed
A strong, noble horse ridden by heroes in adventures.
A steed is a horse, especially one that's strong, spirited, and ridden in battle or on important journeys. The word comes from old stories of knights and warriors, where a knight's steed wasn't just transportation but a trusted companion in dangerous situations.
You'll mostly encounter steed in adventure stories, fantasy novels, and historical tales. In The Lord of the Rings, Gandalf rides a magnificent white steed named Shadowfax. Paul Revere made his famous midnight ride on a brave steed to warn colonists that British troops were coming.
The word carries a sense of nobility and courage that “horse” doesn't quite capture. You wouldn't call a pony giving rides at a fair a steed, but you might describe a powerful horse galloping across a battlefield or racing through a storm as one. When an author writes that a hero “mounted his steed,” they're signaling that something important and probably dangerous is about to happen.
Today, people rarely use steed in everyday conversation (you'd sound odd telling your friend you saw a steed at the stable), but it remains perfect for stories that need that extra dash of adventure and grandeur.