Chameleon

Noun

 * 1) A small to mid-size reptile, of the family Chamaeleonidae, and one of the best known lizard families able to change color and project its long tongue.
 * 2) A person with inconstant behavior; one able to quickly adjust to new circumstances.

Adjective

 * 1) Describing something that changes color.

Thesaurus
alligator, anole, antigorite, bearded lizard, blindworm, box turtle, butterfly, butterfly agama, candy cane, cayman, cheetah, chrysotile, cloud shapes, confetti, crazy quilt, crocodile, diamondback, dragon, false map turtle, firedog, flying dragon, formalist, gavial, gecko, girdle-tailed lizard, glass snake, green turtle, harlequin, hawksbill, hawksbill turtle, iguana, iris, jaguar, kaleidoscope, leatherback, leopard, lizard, mackerel, mackerel sky, marble, marbled paper, matamata, mercury, moire, monitor, moon, mother-of-pearl, mugger, nacre, ocelot, opal, ophite, patchwork quilt, peacock, quicksilver, rainbow, rolling stone, sea turtle, serpentine, serpentine marble, shifting sands, shot silk, soft-shelled turtle, spectrum, stump tail, teju, temporizer, terrapin, the weather, timepleaser, timeserver, tortoise, tortoise shell, trimmer, tuatara, turtle, water, weather vane, weathercock, wheel of fortune, whirligig, zebra

Alternative forms
chamaeleon; chamæleon