warner / one who warns
Active participle (faʿīl pattern) of أَنْذَرَ (to warn). Always paired with بَشِيرٌ (bearer of good news). Noun: نِذَارَةٌ / إِنْذَارٌ (warning).
Every prophet was both a bashīr (giver of good news to believers) and nadhīr (warner to disbelievers) - the dual prophetic message of hope and accountability.