A fad is something that becomes wildly popular for a short time, then fades away almost as quickly as it appeared. Think of fidget spinners: one month every kid in school had one, and a few months later they sat forgotten in desk drawers. That's a classic fad.

Fads spread fast because people want to be part of what's happening right now. Maybe everyone's suddenly wearing slap bracelets, collecting a certain type of trading card, or doing a particular dance. The excitement feels contagious, like the thing will last forever.

But fads burn out. Unlike lasting trends or traditions, they don't have staying power. A video game that remains popular for years isn't a fad. A clothing style that stays fashionable for decades isn't a fad. But a toy that dominates the playground for two months, then disappears? That's definitely a fad.

Adults experience fads too: diet crazes, exercise equipment that everyone buys then never uses, or phone apps that briefly dominate downloads. The word can carry a slightly dismissive tone, suggesting something isn't quite substantial enough to last. When you hear someone say “Oh, that's just a fad,” they're predicting it won't matter much in six months.