sunset

1. :  stipulating the periodic review of government agencies and programs in order to continue their existence sunset laws

US

1. 1 transitive :  to cause or allow (something, such as a law) to lapse, end, or be terminated And yet, even though he was part of the coalition, Obama offered an amendment … that would have sunsetted the merit-based evaluation system for immigrants after five years. — Jake Tapper In an effort to cut back on projects, Google decided to sunset Google Reader … — Tristan Louis

2. 2 intransitive :  to lapse or come to an end :  expire laws that will sunset at the end of the year Since the credit will sunset at the end of 2016, its fate could rest in the hands of a new Congress and a new president—who might not necessarily see the value in reinstating the credit. — Eric S. Peterson

1. 1 :  the apparent passing of the sun below the horizon

2. 2 :  the light and color of the passing of the sun below the horizon

3. 3 :  the time at which the sun sets

1. :  having or being a provision stipulating the termination or repeal of something (as a law, grant, or insurance coverage) on a specified date sunset laws requiring periodic review of programs to justify their continuance