What does “Sleeper” mean?

A sleeper is a watch that the market has overlooked and that some dealers or collectors expect to rise in value. It might be a reference overshadowed by a more famous sibling, a model that was unpopular when new, or a discontinued piece that hasn't yet caught collectors' attention. 'Future classic' is used in the same sense.

Calling something a sleeper is an opinion, not a fact. Some sleepers do become sought after, often after a celebrity sighting, a strong auction result or a shift in taste; many others stay overlooked. For dealers the idea is useful mainly as a buying signal: a sleeper bought at a fair price has limited downside and some possible upside. When a seller describes a watch as a sleeper, check recent sales rather than taking the label at face value, because it is also a popular way to make an ordinary price sound like a bargain.

Example: 'Underrated reference, a real sleeper in my view. Priced well below the more popular version.'