The phrase "rotation period" refers to the amount of time it takes for something to complete one full rotation or spin around its axis. Full definition
With a suspected rotation period of less than 3 days, its activity levels are rather higher as well including energetic flares. (reddots.space)
Wide - field imaging surveys on moderate - size telescopes can now efficiently derive rotation periods for hundreds to thousands of open cluster members, providing unprecedented sample sizes which are ripe for exploration. (arxiv.org)
The fire rotation period calculated per 100 year interval also varied greatly, ca 3000, 4000 and 1800 years over the last 100, 200 and 300 years, respectively. (rstb.royalsocietypublishing.org)