0 present participle of understudy
1 to learn the lines of other actors in a play, so that you can replace them if necessary, for example if they are ill:
He was with the national tour of "The Lion King," understudying the roles of Scar and Pumbaa.
She essentially understudies 11 characters in the musical.
Lisa Fennell, in addition to her role in the chorus, was to understudy Désirée.