Originally meaning an emulator or zealous follower—someone who ardently admires and imitates another. Classical authors use it for devoted students of philosophers like Thucydides or Antisthenes. The Septuagint employs it to translate the Hebrew describing God as 'jealous' (zealous for his own honor). In the New Testament it specifically identifies Simon the Zealot, one of the Twelve. The term likely references the Jewish revolutionary party that resisted Roman rule, though it can also mean simply 'enthusiast' or 'one zealous for the Law.' The word captures both positive devotion and potentially dangerous fanaticism.