Contraband is anything that's illegal to own, buy, sell, or bring across a border. The word describes items that are forbidden by law or by specific rules in a particular place.

At international borders, customs agents search for contraband like smuggled goods that travelers are trying to bring into a country without paying required taxes, or items that are completely prohibited, like certain plants or animals that could harm local ecosystems. In historical times, contraband often referred to goods being smuggled to avoid taxes or wartime blockades.

In schools, teachers might use the term more loosely to describe things students aren't allowed to have in class, like phones during a test or candy during a presentation, though these aren't truly contraband in the legal sense. Real contraband involves actual laws, not just school rules.