Etymology From Middle English son-sett, Sonne set, equivalent to sun + set. In Gower's Confessio Amantis, before 1393.
1
The moment each evening when the sun disappears below the western horizon.
at sunset
’Twas sunset: when the sun will part There comes a sullenness of heart To him who still would look upon The glory of the summer sun.1829, Edgar Allan Poe, “Tamerlane”, in Al Aaraaf, Tamerlane and Minor Poems:
2
The changes in color of the sky before and after sunset.
3
Figuratively The final period of the life of a person or thing.
one's sunset years
'Tis the sunset of life gives me mystical lore.1799, Thomas Campbell, Pleasure of Hope:
4
A set termination date.
The tax increase legislation included a sunset clause requiring renewal to prevent the tax increase from expiring.
We’ll be sunsetting version 1.9 of the software shortly after releasing version 2.0 next quarter.
Last December, Yahoo announced plans to “sunset” more well-known services, including the pioneering social bookmarking service del.icio.us.2011 April 19, Sumit Paul-Choudhury, “Digital legacy: The fate of your online soul”, in NewScientist:
1 more example
Here’s what you need to know about Amazon’s decision to sunset its older e-readers and tablets, and what that means for you.2026 April 9, “Got an Old Kindle? It Might Not Work Anymore. Here’s What to Do.”, in Wirecutter, New York, N.Y.: The New York Times Company, →ISSN, →OCLC: