[1] : The Collaborative International Dictionary of English v.0.48

cactus \cac"tus\, n.; pl. e. cactuses, cacti -timac.
   l., a kind of cactus, gr. ??????. bot.
   any plant of the order cactacae, as the prickly pear and
   the night-blooming cereus. see cereus. they usually have
   leafless stems and branches, often beset with clustered
   thorns, and are mostly natives of the warmer parts of
   america.
   1913 webster

   cactus wren zool., an american wren of the genus
      campylorhynchus, of several species.
      1913 webster
see also:
cactuses cacti cactacae cereus cactus wren campylorhynchus 

[2] : WordNet (r) 2.0

cactus
     n : any spiny succulent plant of the family cactaceae native
         chiefly to arid regions of the new world
     also: cacti pl
see also:
cacti 

[3] : Moby Thesaurus II by Grady Ward, 1.0

21 moby thesaurus words for "cactus":
   bramble, brier, bristle, burr, catchweed, cleavers, goose grass,
   needle, nettle, pine needle, prickle, quill, spicule, spiculum,
   spike, spikelet, spine, sticker, thistle, thorn, yucca

[4] : U.S. Gazetteer (1990)

cactus, tx city, fips 11692
  location: 36.04473 n, 102.01110 w
  population 1990: 1529 478 housing units
  area: 5.3 sq km land, 0.0 sq km water

[5] : U.S. Gazetteer Places (2000)

cactus, tx -- u.s. city in texas
   population 2000:    2538
   housing units 2000: 820
   land area 2000:     2.040434 sq. miles 5.284699 sq. km
   water area 2000:    0.000000 sq. miles 0.000000 sq. km
   total area 2000:    2.040434 sq. miles 5.284699 sq. km
   fips code:            11692
   located within:       texas tx, fips 48
   location:             36.046124 n, 102.002251 w
   zip codes 1990:    
   note: some zip codes may be omitted esp. for suburbs.
   headwords:
    cactus, tx
    cactus

Cactus >> C Words
Cactus, definition of term: Cactus
cactus_pag1.html

Cactus Wren >> C Words
Cactus Wren, definition of term: Cactus Wren
cactus+wren_pag1.html

Crab Cactus >> C Words
Crab Cactus, definition of term: Crab Cactus
crab+cactus_pag1.html