1.
compensatory day off; substitute holiday
A day off granted to an employee as compensation for having worked on a regular day off or holiday.
Common collocations include 代休を取る (to take a comp day), 代休をもらう (to be given a comp day), and 代休を消化する (to use up comp days). Legally distinct from 振替休日 (transferred holiday), which is scheduled in advance before working on a day off. 代休 is granted after the fact, usually at a later date chosen by the employee or employer.