This is the word used to describe the time in the schedule after which television programmes are directed at adult audiences. It is the time, in other words, when children's viewing ends. In New Zealand the television watershed for free-to-air TV is 8.30pm. Broadcasters agree to respect this watershed when they programme their channels.
Watershed is a term used in the United Kingdom (as well as Canada) to describe a time in television schedules beyond which it is permissible to show television programmes which have 'adult content'. It is known in the US as "Safe Harbor". Adult content can be generally defined as having at least some nudity, explicit sexual intercourse, graphic violence, strong language, or drug references or use.