Epoch, Era, Time Period
Noun
じだい
今の時代は、インターネットで何でもかうことができます。
In this era, you can buy anything on the Internet.
明里は、わたしの大学時代の友人です。
Akari is my friend from college.
紫式部は、平安時代中期の女性作家かつ歌人です。
Murasaki Shikibu was a female writer and poet from the mid–Heian period.
You have a period of time and it's called a period or era! Simple!
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.