Peter Mark Roget — born January 18, 1779
Roget was a British medical doctor who, after he retired in 1852, wrote the first modern thesaurus. Roget’s Thesaurus is still commercially successful and widely used. 
A thesaurus is a treasure trove of words. The word thesaurus literally does mean “treasure.” It comes from the Greek word thésauros, which is a storehouse of precious items.
What’s the plural of thesaurus, thesauri or thesauruses? It’s a fascinating topic for dull men to discuss. Although thesauri is technically correct in that it attaches the Latin suffix to the Latin word thēsaurus, both thesauri and thesauruses are commonly used and accepted today. Roget was not only a words man, he also was a numbers man. He invented the slide rule. 
Much of the information for this post is from an excellent article in Mental Floss: “10 Fascinating Facts About the Thesaurus for National Thesaurus Day”
From our Groaners page:
