[{"Bold_text": "verb (used with object)", "List Items": ["to learn (a role) in order to replace the regular actor or actress when necessary.", "to act as understudy to (an actor or actress):to understudy the lead."]}, {"Bold_text": "verb (used without object)", "List Items": ["to act or work as an understudy."]}, {"Bold_text": "noun", "List Items": ["a performer who learns the role of another in order to serve as a replacement if necessary."]}]