Verb
sit in on (third-person singular simple present sits in on, present participle sitting in on, simple past and past participle sat in on)
To attend a private meeting or class without participating.
Parents of younger children often become upset when they are told that they cannot sit in on the psychological assessment.
I hate having people sit in on meetings. Ivanka Trump
In my last band, Soundgarden, I had a couple of different drummers sit in on some stuff and it was fun for me to kind of take a break and watch the band. Matt Cameron
My parents played bridge, and I remember being fascinated watching them. I sometimes got a chance to sit in on a hand, which I loved. But then I didn't actually play on my own for about 30 years. Louis Sachar
Alice went along, at first just observing, but eventually she began to sit in on the games as well. Source: Internet
ABC15 was exclusively invited to sit in on the appointment. Source: Internet
I'd love to sit in on a meeting, flip through the BSC notebook, and be in that group of friends. Source: Internet