any of numerous species of African and Eurasian lizards with a long tongue, a grasping tail, eyeballs that move independently, and the ability to change the colour of its the skin: genus Chamaeleo and other genera
somebody or something changeable; specif a fickle person
chameleonic /-ʹonik/ adj
[Middle English camelion via French and Latinfrom Greek chamaileōn, from chamai on the ground + leōn lion]