February By my logic the first two meanings lack of either a full or new moon in a month can only occur in Februray as the lunar cycle is 29 53 days and the shortest non Feburary month is 30 days Feburary being 28 days or 29 in a bissextile year is the only month that is less than the full cycle and that therefore can miss either a full or new moon in the month As the cycle from dark moon to dark moon is less than 29 53 days it is also impossible to occur outside February As for the fourth meaning two new moons in a month obviously this can not occur in February talk