Armchair literally describes a comfortable chair with supports for your arms on either side. Unlike a simple stool or a kitchen chair, an armchair is designed for relaxing: you can lean back, rest your arms, and settle in with a book or just daydream.

But the word gets more interesting when it's combined with other words to describe someone who thinks they're an expert without actually doing the thing themselves. An armchair quarterback criticizes how a football coach runs plays without ever coaching a team. An armchair detective thinks they could solve crimes better than real investigators, usually while sitting safely at home. An armchair traveler reads about distant places but never actually visits them.

There's nothing wrong with having opinions or learning from your chair. But calling someone an “armchair expert” usually means they're talking confidently about something they've never actually experienced. It's the difference between a student who reads about building a treehouse and one who has actually hammered boards, dealt with wobbly branches, and solved real problems. Both kinds of knowledge matter, but hands-on experience teaches lessons books can't.