[{"Bold_text": "adjective", "List Items": ["not known; not within the range of one's knowledge, experience, or understanding; strange; unfamiliar.", "not discovered, explored, identified, or ascertained:the unknown parts of Antarctica.", "not widely known; not famous; obscure:an unknown writer."]}, {"Bold_text": "noun", "List Items": ["a thing, influence, area, factor, or person that is unknown:the many unknowns in modern medicine; The director cast an unknown in the leading role.", "Mathematics.a symbol representing an unknown quantity: in algebra, analysis, etc., frequently represented by a letter from the last part of the alphabet, asx, y,orz."]}]