"What century is it right now?" "It's the 21st century."
Koichi wants to live at least a century.
I’m afraid my schedule is a little tight that day. I have several meetings related to a Japanese learning festival, which will be the largest one this century.
The account of a generation... this covers a whole generation, and considering how long Japanese people live, this account totals a whole century.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.