The Collaborative International Dictionary of English v.0.48:

Sunset \Sun"set"\, Sunsetting \Sun"set`ting\, n.
   1. The descent of the sun below the horizon; also, the time
      when the sun sets; evening. Also used figuratively.
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            'T is the sunset of life gives me mystical lore.
                                                  --Campbell.
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   2. Hence, the region where the sun sets; the west.
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   Sunset shell (Zool.), a West Indian marine bivalve
      (Tellina radiata) having a smooth shell marked with
      radiating bands of varied colors resembling those seen at
      sunset or before sunrise; -- called also rising sun.
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