The company offers generous grace periods for late payments.

The incubation periods for different diseases can vary greatly.

I have been experiencing heavy menstruation periods lately.

The refractory periods of the neurons vary depending on the type of stimulus.

The rotational periods of the planets in our solar system vary greatly.

The rotation periods of the planets in our solar system vary greatly.

I found several semi-periods in my research.

The synodic periods of the planets vary in length.

During critical periods, children are more sensitive to learning certain skills.

The Sothic periods occur every 1461 years.