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.
      [1913 Webster]

            'T is the sunset of life gives me mystical lore.
                                                  --Campbell.
      [1913 Webster]

   2. Hence, the region where the sun sets; the west.
      [1913 Webster]

   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.
      [1913 Webster]

WordNet (r) 3.0 (2006):

sunset
    adj 1: of a declining industry or technology; "sunset
           industries"
    2: providing for termination; "a program with a sunset
       provision"
    n 1: the time in the evening at which the sun begins to fall
         below the horizon [syn: sunset, sundown] [ant:
         aurora, break of day, break of the day, cockcrow,
         dawn, dawning, daybreak, dayspring, first light,
         morning, sunrise, sunup]
    2: atmospheric phenomena accompanying the daily disappearance of
       the sun
    3: the daily event of the sun sinking below the horizon

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "sunset":
   cardinal points, close of day, cockshut, compass card,
   compass rose, degrees, east, eastward, eve, even, evening,
   evensong, eventide, grayness, half points, lubber line, nightfall,
   north, northeast, northward, northwest, occident, orient,
   quarter points, rhumb, setting sun, shut of day, south, southeast,
   southward, southwest, sundown, sunrise, the expiring day, twilight,
   vesper, west, westward



U.S. Gazetteer Places (2000):

Sunset, AR -- U.S. city in Arkansas
   Population (2000):    348
   Housing Units (2000): 156
   Land area (2000):     0.207533 sq. miles (0.537508 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.207533 sq. miles (0.537508 sq. km)
   FIPS code:            68060
   Located within:       Arkansas (AR), FIPS 05
   Location:             35.221540 N, 90.204965 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Sunset, AR
    Sunset


U.S. Gazetteer Places (2000):

Sunset, FL -- U.S. Census Designated Place in Florida
   Population (2000):    17150
   Housing Units (2000): 5608
   Land area (2000):     3.557659 sq. miles (9.214294 sq. km)
   Water area (2000):    0.013393 sq. miles (0.034687 sq. km)
   Total area (2000):    3.571052 sq. miles (9.248981 sq. km)
   FIPS code:            69812
   Located within:       Florida (FL), FIPS 12
   Location:             25.705820 N, 80.356296 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Sunset, FL
    Sunset


U.S. Gazetteer Places (2000):

Sunset, LA -- U.S. town in Louisiana
   Population (2000):    2352
   Housing Units (2000): 974
   Land area (2000):     3.110804 sq. miles (8.056945 sq. km)
   Water area (2000):    0.027019 sq. miles (0.069978 sq. km)
   Total area (2000):    3.137823 sq. miles (8.126923 sq. km)
   FIPS code:            74060
   Located within:       Louisiana (LA), FIPS 22
   Location:             30.408456 N, 92.066132 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Sunset, LA
    Sunset


U.S. Gazetteer Places (2000):

Sunset, TX -- U.S. city in Texas
   Population (2000):    339
   Housing Units (2000): 151
   Land area (2000):     1.063301 sq. miles (2.753938 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    1.063301 sq. miles (2.753938 sq. km)
   FIPS code:            71264
   Located within:       Texas (TX), FIPS 48
   Location:             33.453823 N, 97.766724 W
   ZIP Codes (1990):     76270
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Sunset, TX
    Sunset


U.S. Gazetteer Places (2000):

Sunset, UT -- U.S. city in Utah
   Population (2000):    5204
   Housing Units (2000): 1832
   Land area (2000):     1.473272 sq. miles (3.815757 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    1.473272 sq. miles (3.815757 sq. km)
   FIPS code:            74480
   Located within:       Utah (UT), FIPS 49
   Location:             41.140544 N, 112.029665 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Sunset, UT
    Sunset