Meaning

noun a complex pattern of constantly changing colors and shapes

noun an optical toy in a tube; it produces symmetrical patterns as bits of colored glass are reflected by mirrors

originThe noun is derived from Ancient Greek καλός (kalós, “beautiful, lovely”) + εἶδος (eîdos, “form, image, shape”) + English -scope (suffix denoting an instrument used for examination or viewing), coined by the British scientist David Brewster (1781–1868) in his 1817 patent for the invention: see the quotation. The verb is derived from the noun.

Etymology from Wiktionary, CC BY-SA 3.0