[{"Bold_text": "verb (used without object)", "List Items": ["to inject a narcotic, especially heroin, directly into a vein.", "to use or enjoy something without restriction:to mainline on TV movies."]}, {"Bold_text": "verb (used with object)", "List Items": ["to inject (a narcotic, especially heroin) directly into a vein.", "to use, enjoy, or imbibe (something) without restriction:mainlining coffee all day long."]}, {"Bold_text": "adjective", "List Items": ["having a principal, established, or widely accepted position; major; mainstream:the membership of mainline churches."]}]