The word(s) "period" appears 15 time(s) in 15 verse(s) in Quran in Muhammad Habib Shakir translation.

(11) And He made in it mountains above its surface, and He blessed therein and made therein its foods, in four periods: alike for the seekers.

(12) So He ordained them seven heavens in two periods, and revealed in every heaven its affair; and We adorned the lower heaven with brilliant stars and (made it) to guard; that is the decree of the Mighty, the Knowing.

(13) And certainly We created the heavens and the earth and what is between them in six periods and there touched Us not any fatigue.

(14) He it is who created the heavens and the earth in six periods, and He is firm in power; He knows that which goes deep down into the earth and that which comes forth out of it, and that which comes down from the heaven and that which goes up into it, and He is with you wherever you are; and Allah sees what you do.

(15) There surely came over man a period of time when he was a thing not worth mentioning.