Doubt is the uncertain feeling you get when you're not sure something is true or will work out. When you doubt whether you studied enough for a test, you're questioning if your preparation was adequate. When a coach doubts a risky play will succeed, she's unsure it's the right choice.

Doubt sits somewhere between certainty and disbelief. You haven't rejected the idea completely, but you haven't accepted it either. A scientist might doubt a new theory until she sees more evidence. Your friend might doubt your claim that you can juggle five balls until you actually demonstrate it.

The word can be a noun or a verb. You might doubt your ability to finish a difficult puzzle (verb), or you might have doubts about whether the weather will cooperate for your camping trip (noun). When something happens without a doubt, it's absolutely certain. When you give someone the benefit of the doubt, you choose to believe them even though you're not completely sure they're being honest.

A small amount of doubt can be healthy: it keeps you checking your work and thinking carefully. But too much doubt can paralyze you, making it hard to make decisions or try new things. The key is learning when doubt is pointing you toward wisdom and when it's just getting in your way.