Warrant means to justify or deserve something. When a situation warrants attention, it's serious enough that people should pay attention to it. If your science project results are surprising enough to warrant a second experiment, they're significant enough to make that extra work worthwhile. A minor scrape doesn't warrant a trip to the emergency room, but a broken bone certainly does.

The word also appears in an important legal context. A warrant is an official document that gives police permission to do something they couldn't otherwise do, like search a house or arrest someone. A judge issues a warrant only when there's good reason to believe a crime has been committed. This legal meaning connects back to the first: the evidence must be strong enough to warrant, or justify, the warrant.

You'll also hear people say something is warranted or unwarranted. An unwarranted accusation is one made without good reason or evidence. If a teacher punishes a student who didn't do anything wrong, that punishment is unwarranted because nothing the student did justified it. When something is warranted, there's solid justification behind it. The root idea stays the same: warrant is about whether something is justified, deserved, or backed by good reasons.