from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A period of 235 lunar months, or about 19 years in the Julian calendar, at the end of which the phases of the moon recur in the same order and on the same days as in the preceding cycle.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A particular approximate common multiple of the tropical year and the synodic month; in other words, the 19-year period over which the lunar phases occur on the same dates.
from the GNU version of the Collaborative International Dictionary of English
According to this doctrine each planet depending on its synodic period (but the Metonic cycle for the Sun, the Egyptian lunar period for the Moon), governs a specific fraction of the native's life, or a specific number of months; then each period is divided into subperiods according to the same proportions, and each subperiod may be further subdivided ad infinitum.