understudy

From Wiktionary

Word parts[change]

under- + study

Pronunciation[change]

Noun[change]

Singular
understudy

Plural
understudies

  1. (countable) An understudy is a person who understudies.

Verb[change]

Plain form
understudy

Third-person singular
understudies

Past tense
understudied

Past participle
understudied

Present participle
understudying

  1. If you understudy, you study or know a role so as to be able to replace the normal performer when required.