Open English Wordnet
Nouns
(n)sunset, sundownthe time in the evening at which the sun begins to fall below the horizon (n)sunsetatmospheric phenomena accompanying the daily disappearance of the sun (n)sunsetthe daily event of the sun sinking below the horizon Adjectives
(s)sunsetof a declining industry or technology“sunset industries” (s)sunsetproviding for termination“a program with a sunset provision”