English Dictionary

synodic month

noun

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.

The synodic month is the period of time it takes for the Moon to return to the same phase, such as from full moon to full moon.

意味（1）

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.

意味（2）

the variably cyclic period from one new moon until the next.