An ambiguous expression which has been applied to various cycles associated with the Moon's motion. See Callippic cycle, Metonic cycle, node cycle, and synodical month.
The period of time between mean conjunctions of the sun and moon (new moon to new moon). This is assumed to be 29 days 12 hours and 793 halakim for calendar purposes.
One of the principal means of establishing a calendar; based on cycles of moon; differed from solar cycles and failed to provide accurate guide to round of the seasons; required constant revision or intercalation. (p. 213)