I. Date: 1874 intransitive verb to study another actor's part in order to substitute in an emergency, transitive verb to prepare (as a part) as ~, II. noun Date: 1882 one who is prepared to act another's part or take over another's duties
UNDERSTUDY
Meaning of UNDERSTUDY in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012