The definition of an understudy is an actor who learns the role of another actor and who performs when that actor is unable.(noun)
An example of an understudy is an actor who learns the star part in the play but who only gets to perform it when the real star can't perform because he has a cold.
See understudy in Webster's New World College Dictionary
noun pl. understudies
See understudy in American Heritage Dictionary 4
verb un·der·stud·ied, un·der·stud·y·ing, un·der·stud·ies verb, transitive
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