[{"Bold_text": "adjective", "List Items": ["happening, coming, made, or done quickly, without warning, or unexpectedly:a sudden attack.Antonyms: gradual", "occurring without transition from the previous form, state, etc.; abrupt :a sudden turn.Antonyms: gradual", "impetuous ; rash .", "Archaic.quickly made or provided.", "Obsolete.unpremeditated."]}, {"Bold_text": "adverb", "List Items": ["Literary.without warning; suddenly."]}, {"Bold_text": "noun", "List Items": ["Obsolete.an unexpected occasion or occurrence."]}]