A decade.
a dot
A period of 100 years is conveyed by the single word century.
History
The sengoku period lasted for about 450 years
A period of seven years is called a septennium.
generation
sevennenium
100 years is a "century."
term millennium
A decade.
That's called a millenium.
People often call this an Ice Age. The last glacial period began about 100,000 years ago and lasted until 25,000 years ago.
If you're in the first 1-2 years of your period, it's normal. If not, call a doctor.
Procession of the Equinox
Long-period comet
Probably a decadent because a decade is a period of 10 years