Yes, periods is a Scrabble word!

Noun

1. An amount of time

2. The interval taken to complete one cycle of a regularly repeating phenomenon

3. (ice hockey) one of three divisions into which play is divided in hockey games

4. A unit of geological time during which a system of rocks formed

5. The end or completion of something

6. The monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause

7. A punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations