Webster's Revised Unabridged Dictionary · 1913

Chameleon

Chameleon (kȧ*mē"le*un) , noun

[Latin Chamaeleon, Greek chamaile`wn, lit., “ground lion;” chamai` on the ground + le`wn lion. See Humble, and Lion.]

1.
(Zoology) A lizardlike reptile of the genus Chamaleo, 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.
ground lion;

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 Iguanida. They are more slender in form than the true chameleons, but have the same power of changing their colors.

2.
a person who changes opinions, ideas, or behavior to suit the prevailing social climate; an opportunist.
Collocations (1)
Chameleon mineral (Chemistry) , 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.