a phase of the moon when the moon's visible surface area is decreasing
Waning
a phase of the moon when the moon appears to grow larger each night
Waxing
a specific period in a series of events in which something may change or develop
Phases
a thing that has the shape of a single curve, broader in the center and it gets smaller to a point at each end.
Crescent
four equal parts into which something can be divided
Quarter