sunset

(noun) the time in the evening at which the sun begins to fall below the horizon. Synonyms: sundown.

(noun) atmospheric phenomena accompanying the daily disappearance of the sun.

(noun) the daily event of the sun sinking below the horizon.

(adj) of a declining industry or technology. Examples: "Sunset industries."

(adj) providing for termination. Synonyms: sunset(prenominal). Examples: "A program with a sunset provision."