[{"Bold_text": "adjective", "List Items": ["made or done without previous preparation:an impromptu address to the unexpected crowds.", "suddenly or hastily prepared, made, etc.:an impromptu dinner.", "improvised; having the character of an improvisation."]}, {"Bold_text": "adverb", "List Items": ["without preparation:verses written impromptu."]}, {"Bold_text": "noun", "List Items": ["something impromptu; an impromptu speech, musical composition, performance, etc.", "a character piece for piano common in the 19th century and having, despite its title, a clear-cut form."]}]