Most scientific words grow slowly. Kaleidoscope was invented in a single year, by the man who invented the object.

David Brewster, a Scottish scientist who lived from 1781 to 1868, coined the word in 1817. The Brewster Kaleidoscope Society says the instrument was invented and exhibited in 1816. Wikipedia says he first noticed the effect in experiments in 1814 and refined it in 1815.

Etymonline says the word combines Greek roots meaning "beautiful" and "shape," with -scope added on the model of telescope. Wikipedia names the pieces: kalos, "beautiful," eidos, "form or appearance," and skopeo, "to look or examine." The result is roughly "observer of beautiful forms."

The patent story is disputed. Etymonline says Brewster never obtained a patent. Wikipedia lists British patent no. 4136, granted on 10 July 1817, and cites a contemporary journal, the Repertory of Patent Inventions. Britannica also says it was patented in 1817.

The Brewster Society reconciles the accounts. It says a patent was granted, but adds that "there was some fault with the patent registration," which kept Brewster from earning money from it. The safest reading is that a patent was issued but did not protect him.

The sources agree on what followed. Copies appeared fast. Wikipedia says Londoners copied the instrument before the original maker had enough to sell, and estimates 200,000 were sold in London and Paris in about three months. Brewster judged that at most 1,000 of them were authorized.

Brewster published his Treatise on the Kaleidoscope in 1819 to explain the principles and correct construction.

The word jumped from the tube to the language almost at once. Etymonline records the figurative sense, a constantly changing pattern, in 1819 in Lord Byron's writing. His publisher had sent him one of the toys. A verb form is recorded by 1891.

Brewster's coinage also set a pattern. Etymonline says Charles Wheatstone, who lived from 1802 to 1875, invented the kaleidophone in 1827 to make sound waves visible.

A kaleidoscope, then, is named for what the viewer does: look at beautiful forms.