To thieve means to steal. When someone thieves, they take things that don't belong to them, usually in a sneaky or secretive way. A person who thieves might slip a candy bar into their pocket at a store, or take money from someone's desk when they're not looking.

The word suggests more active, deliberate stealing than just finding something and keeping it. A thief is someone who thieves, and thievery is the act or practice of stealing. In old stories and legends, you'll often read about thieves breaking into castles or sneaking through villages at night. Even today, we talk about cat burglars and pickpockets as types of thieves.

Thieving can destroy trust. When someone thieves from their friends, classroom, or family, they damage relationships and can face serious consequences.

You'll see this word used more in British English than American English, where people more commonly just say “steal.”