What does the word protean mean?

Usage examples for protean

  1. When, however, one reflects that amulets, in some one of their protean forms, have been invested with supernatural preventive and healing powers by the people of all lands and epochs, and that they have been worn not only by kings and princes, but by philosophers, prelates, and physicians of eminence as well, it is evident that the subject deserves more than a passing consideration. – Primitive Psycho-Therapy and Quackery by Robert Means Lawrence