[{"Bold_text": "noun", "List Items": ["a person or thing that kills . kill .", "killer whale killer whale.", "a device used by a post office for printing cancellations on postage stamps.", "a mark of cancellation made on a postage stamp.", "Slang.something or someone having a formidable impact, devastating effect, etc.:The math test was a real killer."]}, {"Bold_text": "adjective", "List Items": ["severe; powerful:a killer cold.", "very difficult or demanding:a killer chess tournament.", "highly effective; superior:a killer recipe for fried chicken."]}]