the calendar
a two week period
fortnight
100
Bonus
happening every 200 years
bicentennial
the time taken for the moon to undergo all phases
lunar month
300
Bonus
the beginning of a distinct period of history
epoch
a long distinct period of history
era
a second inserted in our local time to stay close to solar time
leap second
a year containing 366 days
leap year
an indefinite period of time
eon