Month
Symbol: M
One month is the period of time related to one circle of a satellite around his planet. For the moon this time lasts between 29.272 and 29.833 days. The different periods are a result of the different speeds of earth and moon while moving around the sun.
The average time (=synodic month) is 29 days, 12 hours, 44 minutes (=29.5306 days or 2,551,440 seconds).