zealot

One who is zealous, especially excessively so.

A fanatically committed person.

A member of a Jewish movement of the first century AD that fought against Roman rule in Palestine as incompatible with strict monotheism.

One who is zealous or full of zeal; one carried away by excess of zeal; an immoderate partizan: generally in a disparaging sense.

[capitalized] One of a fanatical sect or party (the Zelotæ) among the Jews of Palestine under Roman dominion, who on account of their excesses in behalf of the Mosaic law were also called Sicarii or Assassins.