Dictionarysunset
/ˈsʌnˌsɛt/ 
noun
The time of day when the sun disappears below the western horizon.
The changes in color of the sky at sunset.
- last
- terminal
- twilight
- end
- final act
- swansong
- dusk
- nightfall
- sundown
- twilight
verb
To phase out.
We'll be sunsetting version 1.9 of the software shortly after releasing version 2.0 next quarter.