A foe is an enemy or opponent, someone actively working against you or wishing you harm. In stories, the hero's foe might be a villain plotting to steal a treasure or conquer a kingdom. In sports, your foe is the team you're competing against, trying to defeat you on the field.

The word carries a more serious tone than “opponent” or “rival.” While you might respect a rival and shake hands after a game, a foe suggests deeper conflict or hostility. In The Lord of the Rings, Sauron is the foe of all free peoples. In chess, your opponent sits across from you, but in war, armies face their foes.

You'll often see foe paired with “friend” in the phrase “friend or foe,” meaning someone must figure out whether another person is on their side or against them. A guard at a castle gate might call out, “Friend or foe?” to identify approaching strangers.

While we use foe less in everyday conversation than words like “enemy,” it appears frequently in literature, history, and formal writing. When Winston Churchill spoke of standing against Britain's foes during World War II, the word captured the gravity of facing a serious, determined enemy.