Easton's Bible Dictionary

Zealots - a sect of Jews which originated with Judas the Gaulonite (Acts 5:37). They refused to pay tribute to the Romans, on the ground that this was a violation of the principle that God was the only king of Israel. They rebelled against the Romans, but were soon scattered, and became a lawless band of mere brigands. They were afterwards called Sicarii, from their use of the sica, i.e., the Roman dagger.