To snoop means to secretly look through someone's belongings or private information when you have no right to do so. A person who snoops might read their sibling's diary, peek at text messages on someone's phone when they leave the room, or rifle through desk drawers looking for hidden presents before a birthday.

Snooping is different from honest curiosity or legitimate investigation. If your teacher asks to see your homework, that's not snooping because it's their job to check your work. But if your friend goes through your backpack without permission, hunting for secrets, that's definitely snooping.

The word suggests sneakiness and invasion of privacy. When someone accuses you of snooping around, they're saying you're poking into matters that don't concern you. A snoop (as a noun) is someone who regularly pries into other people's business.

People snoop for different reasons: sometimes from curiosity, sometimes from suspicion, sometimes just from nosiness. But whatever the reason, snooping breaks trust. When someone discovers they've been snooped on, they usually feel violated and angry, even if the snoop didn't find anything especially secret.