Originally, of course, the term month meant the span of a full set of four phases of the Moon, e.g. from full moon to full moon, or from new moon to new moon, terms which render the appearance of the Moon to the inhabitants of Earth. On the Moon itself, this lunar month of 29.53 Earth days would rather appear to denote a full set of phases of Earth, e.g. full earth to full earth, except that this definition of month would seem irrelevant to anyone living on the Farside from which Earth was never visible. Rather, to the Lunar Settlers, this period, called a lunation by our astronomers, will simply signify the period from sunrise to sunrise or sunset to sunset on their world. Accordingly, they might well prefer to call it simply the sunth, especially since this term is less stuffy than lunation and avoids confusion with Earth’s calendar months of Roman origin which do not coincide at all since they average about a day longer in order to divide the year into twelve with no leftover. The Sunth then would be the natural way of reckoning the passage of time on the Moon.