1. a person who is extremely enthusiastic about something, especially a cause or belief
Usage: often implies excessive or fanatical devotion
2. a member of an ancient Jewish sect that fought against Roman rule in Palestine
Usage: historical; capitalized when referring to the specific group

Examples

• The environmental zealot refused to use any plastic products.
• He was such a fitness zealot that he exercised three hours every day.
• The political zealot couldn’t tolerate any opposing viewpoints.
• She became a zealot for organic farming after reading about pesticides.
• The Zealots were known for their fierce resistance to Roman occupation.
• His zealot-like devotion to the cause worried his friends.
• The religious zealot preached on street corners every weekend.