A kaleidoscope is a child's toy, a tube with a series of mirrors at one end that reflect multiple images of colored bits of glass or toys that move, creating constantly-changing images as you turn the tube.
The toy kaleidoscope was invented around 1817 by Sir David Brewster. He took the name for his ever-changing picture tube from the Greek words kalos, "beautiful," combined with eidos, "shape." The "scope" part came from the Greek verb skopein, "to look," which can be found in many words referring to looking, including "telescope" and "microscope." The poet Lord Byron broadened the meaning of the word, giving it the sense of a "constantly changing pattern."