kaleidoscope

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A tube-shaped optical instrument that is rotated to produce a succession of symmetrical designs by means of mirrors reflecting the constantly changing patterns made by bits of colored glass at one end of the tube.
2. n. A constantly changing set of colors.
3. n. A series of changing phases or events: a kaleidoscope of illusions.

Century Dictionary and Cyclopedia

1. n. An optical instrument creating and exhibiting, by reflection, a variety of beautiful colors and symmetrical forms. In its simplest form the instrument consists of a tube containing two reflecting surfaces inclined toward each other at any angle which is an aliquot part of 360°. A clear eye-glass is placed immediately against one end of the mirrors and a similar glass at their other end; the tube is continued a little beyond this second glass, and its termination is closed by a disk of ground glass. In the cell thus formed are placed beads, pieces of colored glass, or other small, bright-colored, diaphanous objects, and the changing of their positions by rotating the tube produces, by the repeated reflection in the mirrors, different symmetrical figures. The polyangular kaleidoscope multiplies the effect by having three or four mirrors; a larger number destroys the symmetry of combination. Besides the use of the kaleidoscope as a toy, it serves the practical purpose of furnishing an endless variety of patterns for decorative work. Sir David Brewster invented the instrument about 1815, although the idea of it had been vaguely suggested before. He also made it applicable to distant objects by replacing the object-box at the outer end with a double-convex lens, controlled by an adjusting-screw.

Wiktionary

1. n. A tube of mirrors containing loose coloured beads etc. that is rotated to produce a succession of symmetrical designs
2. n. A constantly changing set of colours, or other things

GNU Webster's 1913

1. n. An instrument invented by Sir David Brewster, which contains loose fragments of colored glass, etc., and reflecting surfaces so arranged that changes of position exhibit its contents in an endless variety of beautiful colors and symmetrical forms. It has been much employed in arts of design.

WordNet 3.0

1. n. a complex pattern of constantly changing colors and shapes
2. n. an optical toy in a tube; it produces symmetrical patterns as bits of colored glass are reflected by mirrors