An octopus can squeeze its boneless body through a long narrow tube, or compact itself into a shallow underwater cave. This ability to take on different forms or characteristics is described by the word “protean,” meaning “extremely variable.” The word comes from the name of the oldest sea god in Greek mythology, Proteus.

Example:  “The protean skin coloration of animals like the chameleon and the reef squid allows them to blend in almost invisibly with their surroundings.”