Definition of cooldown:
(n) :
(video games) The minimum length of time that the player needs to wait after using an ability or item before it can be used again.
(n) :
(by extension) Any rest period between sessions of an activity or event.
(n) :
(sports) The rest period between sets or workout sessions, when cooling of body temperature may occur.
(n) :
(by extension) A particular ability with a powerful effect but long cooldown period, making it important to track when it was last used and when it can be used again.