sit in for - definition and synonyms

phrasal verb [transitive]
present tense
I/you/we/theysit in for
he/she/itsits in for
present participlesitting in for
past tensesat in for
past participlesat in for
  1. sit in for someone to take the place of someone temporarily

    I’ll be sitting in for the secretary at the meeting tonight.

See also main entry: sit