The Collaborative International Dictionary of English v.0.48:

Trinity \Trin"i*ty\, n. [OE. trinitee, F. trinit['e], L.
   trinitas, fr. trini three each. See Trinal.]
   1. (Christian Theol.) The union of three persons (the Father,
      the Son, and the Holy Ghost) in one Godhead, so that all
      the three are one God as to substance, but three persons
      as to individuality.
      [1913 Webster]

   2. Any union of three in one; three units treated as one; a
      triad, as the Hindu trinity, or Trimurti.
      [1913 Webster]

   3. Any symbol of the Trinity employed in Christian art,
      especially the triangle.
      [1913 Webster]

   Trinity House, an institution in London for promoting
      commerce and navigation, by licensing pilots, ordering and
      erecting beacons, and the like.

   Trinity Sunday, the Sunday next after Whitsunday; -- so
      called from the feast held on that day in honor of the
      Holy Trinity.

   Trinity term. (Law) See the Note under Term, n., 5.
      [1913 Webster]

WordNet (r) 3.0 (2006):

trinity
    n 1: the cardinal number that is the sum of one and one and one
         [syn: three, 3, III, trio, threesome, tierce,
         leash, troika, triad, trine, trinity, ternary,
         ternion, triplet, tercet, terzetto, trey, deuce-
         ace]
    2: the union of the Father and Son and Holy Ghost in one Godhead
       [syn: Trinity, Holy Trinity, Blessed Trinity, Sacred
       Trinity]
    3: three people considered as a unit [syn: trio, threesome,
       triad, trinity]

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "trinity":
   clover, deuce-ace, leash, set of three, shamrock, tercet, ternary,
   ternion, terzetto, three, threeness, threesome, tierce, trefoil,
   trey, triad, triality, trialogue, triangle, tricorn, trident,
   triennium, trihedron, trilogy, trimester, trine, trinomial, trio,
   triphthong, triple, triple crown, triple threat, tripleness,
   triplet, triplicity, triplopy, tripod, triptych, trireme, triseme,
   triskelion, trisul, triumvirate, triune, triunity, trivet,
   troika



Easton's 1897 Bible Dictionary:

Trinity
   a word not found in Scripture, but used to express the doctrine
   of the unity of God as subsisting in three distinct Persons.
   This word is derived from the Gr. trias, first used by
   Theophilus (A.D. 168-183), or from the Lat. trinitas, first used
   by Tertullian (A.D. 220), to express this doctrine. The
   propositions involved in the doctrine are these: 1. That God is
   one, and that there is but one God (Deut. 6:4; 1 Kings 8:60;
   Isa. 44:6; Mark 12:29, 32; John 10:30). 2. That the Father is a
   distinct divine Person (hypostasis, subsistentia, persona,
   suppositum intellectuale), distinct from the Son and the Holy
   Spirit. 3. That Jesus Christ was truly God, and yet was a Person
   distinct from the Father and the Holy Spirit. 4. That the Holy
   Spirit is also a distinct divine Person.


The Devil's Dictionary (1881-1906):

TRINITY, n.  In the multiplex theism of certain Christian churches,
three entirely distinct deities consistent with only one.  Subordinate
deities of the polytheistic faith, such as devils and angels, are not
dowered with the power of combination, and must urge individually
their claims to adoration and propitiation.  The Trinity is one of the
most sublime mysteries of our holy religion.  In rejecting it because
it is incomprehensible, Unitarians betray their inadequate sense of
theological fundamentals.  In religion we believe only what we do not
understand, except in the instance of an intelligible doctrine that
contradicts an incomprehensible one.  In that case we believe the
former as a part of the latter.


U.S. Gazetteer Counties (2000):

Trinity -- U.S. County in California
   Population (2000):    13022
   Housing Units (2000): 7980
   Land area (2000):     3178.607390 sq. miles (8232.554997 sq. km)
   Water area (2000):    28.933587 sq. miles (74.937644 sq. km)
   Total area (2000):    3207.540977 sq. miles (8307.492641 sq. km)
   Located within:       California (CA), FIPS 06
   Location:             40.667129 N, 123.070397 W
   Headwords:
    Trinity
    Trinity, CA
    Trinity County
    Trinity County, CA


U.S. Gazetteer Counties (2000):

Trinity -- U.S. County in Texas
   Population (2000):    13779
   Housing Units (2000): 8141
   Land area (2000):     692.844560 sq. miles (1794.459095 sq. km)
   Water area (2000):    21.158212 sq. miles (54.799514 sq. km)
   Total area (2000):    714.002772 sq. miles (1849.258609 sq. km)
   Located within:       Texas (TX), FIPS 48
   Location:             31.008608 N, 95.204909 W
   Headwords:
    Trinity
    Trinity, TX
    Trinity County
    Trinity County, TX


U.S. Gazetteer Places (2000):

Trinity, AL -- U.S. town in Alabama
   Population (2000):    1841
   Housing Units (2000): 728
   Land area (2000):     3.620374 sq. miles (9.376724 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    3.620374 sq. miles (9.376724 sq. km)
   FIPS code:            76872
   Located within:       Alabama (AL), FIPS 01
   Location:             34.603808 N, 87.086137 W
   ZIP Codes (1990):     35673
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Trinity, AL
    Trinity


U.S. Gazetteer Places (2000):

Trinity, FL -- U.S. Census Designated Place in Florida
   Population (2000):    4279
   Housing Units (2000): 1863
   Land area (2000):     4.721134 sq. miles (12.227680 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    4.721134 sq. miles (12.227680 sq. km)
   FIPS code:            72442
   Located within:       Florida (FL), FIPS 12
   Location:             28.177854 N, 82.671139 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Trinity, FL
    Trinity


U.S. Gazetteer Places (2000):

Trinity, NC -- U.S. city in North Carolina
   Population (2000):    6690
   Housing Units (2000): 2759
   Land area (2000):     16.897125 sq. miles (43.763351 sq. km)
   Water area (2000):    0.096566 sq. miles (0.250104 sq. km)
   Total area (2000):    16.993691 sq. miles (44.013455 sq. km)
   FIPS code:            68400
   Located within:       North Carolina (NC), FIPS 37
   Location:             35.873522 N, 80.010158 W
   ZIP Codes (1990):     27370
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Trinity, NC
    Trinity


U.S. Gazetteer Places (2000):

Trinity, TX -- U.S. city in Texas
   Population (2000):    2721
   Housing Units (2000): 1284
   Land area (2000):     3.778128 sq. miles (9.785305 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    3.778128 sq. miles (9.785305 sq. km)
   FIPS code:            73664
   Located within:       Texas (TX), FIPS 48
   Location:             30.945495 N, 95.375599 W
   ZIP Codes (1990):     75862
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Trinity, TX
    Trinity