Lunation /(?)/

Lu·na·tion

Lunation

n.
  1. The period of a synodic revolution of the moon, or the time from one new moon to the next; varying in length, at different times, from about 29<frac:1_4/ to 29<frac:5_6/ days, the average length being 29 d., 12h., 44m., 2.9s.