"period" - key terms from Wikipedia

accounting period
amarna period
archaic period
baroque period
base period
classic period
classical period
colonial period
conversion period
during the period
during this period
early modern period
edo period
eruptive period
first period
glacial period
heian period
hellenistic period
incubation period
intermediate period
interwar period
joseon period
kamakura period
last glacial period
medieval period
medieval warm period
meiji period
migration period
mourning period
muromachi period
nara period
orbital period
overtime period
payback period
period
period	of time
predynastic period
refractory period
rotation period
second intermediate period
second period
sengoku period
spring and autumn period
third period
three kingdoms period
time period
uruk period
vedic period
waiting period
warring states period