A hundred years is a century.
A word for a hundred years is a century. A word for fifty years is half a century.
century
Centenary
The word bicentennial.
sesquicentennial
There are a hundred years in a century.
century
"Bicentennial" means something that is two hundred years old.
The word is... bicentennial.
Bientum. Coming for the Latin word "Centum" meaning one hundred.
Millenium Actually, a millennium is a thousand years. That is ten centuries NOT a hundred centuries. There is no single word to describe a hundred centuries.
A period of 100 years is conveyed by the single word century.