sunset (Noun) — The daily event of the sun sinking below the horizon.
sunset (Noun) — The time in the evening at which the sun begins to fall below the horizon.
sunset (Noun) — Atmospheric phenomena accompanying the daily disappearance of the sun.
sunset (Adjective) — Of a declining industry or technology. ex. "sunset industries"
sunset (Adjective) — Providing for termination. ex. "a program with a sunset provision"