sit in on - definition and synonyms

phrasal verb [transitive]
present tense
I/you/we/theysit in on
he/she/itsits in on
present participlesitting in on
past tensesat in on
past participlesat in on
  1. sit in on something to go to a meeting or a class although you are not directly involved in it

    Do you mind if I sit in on your class this afternoon?

See also main entry: sit