nightmare noun Stress: first syllable 🤍 Save Syllables: night-mare (2) English Definition A frightening or unpleasant dream. Example Sentence I had a nightmare last night. US IPA /ˈnaɪtmer/ 🔊 Listen US UK IPA /ˈnaɪtmeə(r)/ 🔊 Listen UK Synonyms bad dream ordeal horror terror Antonyms daydream pleasant dream joy Share this Word Facebook WhatsApp X Telegram Copy Link