The term 'First Appearance' refers to the initial occurrence of something. In this context, it could refer to the DEBUT, ONSET, or PREMIERE of a person, event, or object. The term 'DEBUT' is used to describe the first public appearance of a person or thing, while 'ONSET' is used to describe the beginning of something, such as an illness or a process. Finally, 'PREMIERE' is used to describe the first public performance of a play, movie, or other form of entertainment.