Period is a noun.
1. A definite portion of time.
2. The duration of a lesson in a school.
3. The monthly discharge from uterus of a woman. Also known as Menstrual Period.
4. Full Stop. Also, a tone of finality.
1. The period spent with Akash was the best in my life.
2. The English period was very boring today.
3. She has severe stomach ache during her periods.
4. I told you to do this. That's all. Period.