a month of approximately 29.53 days, measured from a lunar phase until the return of that same phase. The long-term average duration is 29.530 588 days (29 d 12 h 44 min 2.8 s), or about 29 ½ days.

(astronomy) The apparent orbital period of a planet as seen from Earth.

plural of synodic period

plural of synodic month

In Orthodox Churches, the governing body composed of the metropolitan bishops and presided by the patriarch.

A member of a church synod.

plural of synodsman