sun ‧ set /ˈsʌnset/ BrE AmE noun
1 . [uncountable] the time of day when the sun disappears and night begins
at sunset
We take the flag down at sunset.
2 . [uncountable and countable] the coloured part of the sky where the sun is disappearing at the end of the day ⇨ dusk :
a glorious sunset