noun, noun or participle which takes 'suru', transitive verb
listening in; attending as an observer; sitting in on
Used for attending a formal session (lecture, court hearing, parliamentary session, meeting) as a non-participating listener or observer. Often used with する to mean 'to audit' or 'to observe'.
裁判の傍聴に行く。
I go to observe the trial.
講義を傍聴する許可をもらった。
I got permission to audit the lecture.