Paranoid means having irrational fears that others are trying to harm you, watch you, or work against you, even when there's no real evidence. A paranoid person might be convinced their classmates are whispering about them when they're actually just talking about homework, or believe someone is plotting against them when that person barely knows they exist.

The word comes from a more serious mental health condition called paranoia, but people use it more casually too. You might jokingly say you're feeling paranoid if you forgot to study and now worry the teacher will call on you specifically, even though there's no reason to think that.

Being paranoid is different from being cautious or careful. A careful person locks their bike because bike theft happens sometimes. A paranoid person might use three locks, check on their bike every ten minutes, and suspect everyone nearby of planning to steal it. Paranoid thinking turns ordinary situations into imagined threats.

Someone in a paranoid state sees danger and deception everywhere, which makes it hard to trust people or feel safe. It's exhausting to live this way, constantly on guard against threats that aren't real. While everyone feels suspicious or worried sometimes, paranoia means these feelings take over even when everything's actually fine.