The Collaborative International Dictionary of English v.0.48:

chamaeleon \chamaeleon\ n. [L. Chamaeleon, Gr. chamaile`wn,
   lit., "ground lion;" chamai` on the ground + le`wn lion.]
   (Zool.)
   a lizard of Africa and Madagascar able to change skin color
   and having a projectile tongue.

   Syn: chameleon.
        [WordNet 1.5]

The Collaborative International Dictionary of English v.0.48:

Chamaeleon \Chamaeleon\ n. (Astronomy)
   a small constellation in the southern skies between Hydrus
   and Musca.

   Syn: Chameleon.
        [PJC] Chamaeleonidae

The Collaborative International Dictionary of English v.0.48:

Chameleon \Cha*me"le*on\ (k[.a]*m[=e]"l[-e]*[u^]n), n. [L.
   Chamaeleon, Gr. chamaile`wn, lit., "ground lion;" chamai` on
   the ground + le`wn lion. See Humble, and Lion.] (Zool.)
   1. A lizardlike reptile of the genus Cham[ae]leo, of
      several species, found in Africa, Asia, and Europe. The
      skin is covered with fine granulations; it has eyes which
      can move separately, the tail is prehensile, and the body
      is much compressed laterally, giving it a high back. It is
      remarkable for its ability to change the color of its skin
      to blend with its surroundings. [Also sometimes spelled
      chamaeleon.]
      [1913 Webster +PJC]

   Note: Its color changes more or less with the color of the
         objects about it, or with its temper when disturbed. In
         a cool, dark place it is nearly white, or grayish; on
         admitting the light, it changes to brown, bottle-green,
         or blood red, of various shades, and more or less
         mottled in arrangment. The American chameleons belong
         to Anolis and allied genera of the family
         Iguanid[ae]. They are more slender in form than the
         true chameleons, but have the same power of changing
         their colors.
         [1913 Webster]

   2. a person who changes opinions, ideas, or behavior to suit
      the prevailing social climate; an opportunist.
      [PJC]

   Chameleon mineral (Chem.), the compound called potassium
      permanganate, a dark violet, crystalline substance,
      KMnO4, which in formation passes through a peculiar
      succession of color from green to blue, purple, red, etc.
      See Potassium permanganate, under Potassium.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Chamaeleon
    n 1: a faint constellation in the polar region of the southern
         hemisphere near Apus and Mensa [syn: Chamaeleon,
         Chameleon]
    2: lizard of Africa and Madagascar able to change skin color and
       having a projectile tongue [syn: chameleon, chamaeleon]