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

tortoise \tor"toise\, n. oe. tortuce, fr. of. tortis crooked,
   fr. l. tortus twisted, crooked, contorted, p. p. of torquere,
   tortum, to wind; cf. f. tortue tortoise, ll. tortuca,
   tartuca, pr. tortesa crookedness, tortis crooked. so called
   in allusion to its crooked feet. see torture.
   1. zool. any one of numerous species of reptiles of the
      order testudinata.
      1913 webster

   note: the term is applied especially to the land and
         fresh-water species, while the marine species are
         generally called turtles, but the terms tortoise and
         turtle are used synonymously by many writers. see
         testudinata, terrapin, and turtle.
         1913 webster

   2. rom. antiq. same as testudo, 2.
      1913 webster

   box tortoise, land tortoise, etc. see under box,
      land, etc.

   painted tortoise. zool. see painted turtle, under
      painted.

   soft-shell tortoise. zool. see trionyx.

   spotted tortoise. zool. a small american fresh-water
      tortoise chelopus guttatus or nanemys guttatus
      having a blackish carapace on which are scattered round
      yellow spots.

   tortoise beetle zool., any one of numerous species of
      small tortoise-shaped beetles. many of them have a
      brilliant metallic luster. the larvae feed upon the leaves
      of various plants, and protect themselves beneath a mass
      of dried excrement held over the back by means of the
      caudal spines. the golden tortoise beetle cassida
      aurichalcea is found on the morning-glory vine and
      allied plants.

   tortoise plant. bot. see elephant's foot, under
      elephant.

   tortoise shell, the substance of the shell or horny plates
      of several species of sea turtles, especially of the
      hawkbill turtle. it is used in inlaying and in the
      manufacture of various ornamental articles.

   tortoise-shell butterfly zool., any one of several
      species of handsomely colored butterflies of the genus
      aglais, as aglais milberti, and aglais urticae, both
      of which, in the larva state, feed upon nettles.

   tortoise-shell turtle zool., the hawkbill turtle. see
      hawkbill.
      1913 webster
see also:
torture testudinata terrapin turtle testudo box tortoise 
land tortoise box land painted tortoise painted turtle 
painted soft-shell tortoise trionyx spotted tortoise chelopus guttatus 
nanemys guttatus tortoise beetle cassida aurichalcea tortoise plant elephant's foot 
elephant tortoise shell tortoise-shell butterfly aglais aglais milberti 
aglais urticae tortoise-shell turtle hawkbill 

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

52 moby thesaurus words for "tortoise shell":
   dalmatian, antigorite, burele, butterfly, candy cane, chameleon,
   chatoyant, cheetah, chrysotile, confetti, crazy quilt, firedog,
   harlequin, iridal, iridescent, iridial, iridian, iris, irisated,
   irised, jaguar, leopard, mackerel, mackerel sky, marble,
   marbled paper, moire, mother-of-pearl, nacre, nacred, nacreous,
   nacry, ocelot, opal, opalescent, opaline, opaloid, ophite,
   patchwork quilt, pavonian, pavonine, peacock, pearlish, pearly,
   rainbow, rainbowlike, rainbowy, serpentine, serpentine marble,
   shot silk, spectrum, zebra

Shell >> S Words
Shell, definition of term: Shell
shell_pag1.html

Tortoise >> T Words
Tortoise, definition of term: Tortoise
tortoise_pag1.html

Shell Corporati >> S Words
Shell Corporati, definition of term: Shell Corporati
shell+corporati_pag1.html

Shell Script >> S Words
Shell Script, definition of term: Shell Script
shell+script_pag1.html

Shell Out >> S Words
Shell Out, definition of term: Shell Out
shell+out_pag1.html

Secure Shell >> S Words
Secure Shell, definition of term: Secure Shell
secure+shell_pag1.html

C Shell >> C Words
C Shell, definition of term: C Shell
c+shell_pag1.html

Desert Tortoise >> D Words
Desert Tortoise, definition of term: Desert Tortoise
desert+tortoise_pag1.html

Gopher Tortoise >> G Words
Gopher Tortoise, definition of term: Gopher Tortoise
gopher+tortoise_pag1.html

Box Tortoise >> B Words
Box Tortoise, definition of term: Box Tortoise
box+tortoise_pag1.html