Zealots were a political/philosophic movement in first century (what I call) Israel. They were (if I can put it this way) a sort of uncouth bunch who thought the only way to free themselves from Roman rule was to oppose the Romans with force.
That was their platform. They did not take into account that the Roman's were a huge military power that was ruthless when antagonized. As these things go, Rome was a pretty good ruler. At least they knew the difference between meaningful opposition and tolerance of differences.
The zealots did not see Rome that way. They believed that any interference was too much interference.
That's when Rome got upset and the first Jewish War of 65 AD or so began. It was like sticking your arm in a hornet's nest. The Zealots had gained the largely unwelcome wrath of Rome. The zealots were unlucky (in a way). If they had picked a time that a warrior/emperor was not leader, their opposition may have evaporated. It would be like hitting a marshmallow. Rome may have considered it an internal affair. They had up to this point. Even though some of the Pharisee priests supported the Zealots, the alliance was destroyed by the unwillingness to negotiate further.
Anyone who is really dedicated can be termed a Zealot in modern times. I am using the term to describe someone that is Zealous. You could look up Galatians 1:11 - 14 to see how Paul used the term. This connection between Paul and Jewish leaders (including Zealots) is really hotly debated. It's another hornet's nest.
