From the web site "www.last-names.net", POINDEXTER is described thus:
(origin: Fr.) The same as Hotspur, or spur the steed; point being derived from pungo, to pierce, to prick; and dexter, right, as opposed to left; a word expressive of readiness of limbs, adroitness, expertness, and skill. Today, you will find Poingdestre's around the world, in Australia, New Zealand, England and even in America. But you find few Poindexter's outside the U.S. where our immigrant's Latinize version is used.
Poingdestre or Poindexter?
According to Landers, educated persons of the Renaissance would Latinize their surname to, as we would add Dr. to the begriming or our name or "PhD" at the end. Poindexter is the Latinized form of the old Jersey surname Poingdestre. Since our immigrant, George, was educated at Oxford, he probably used the Latin form in his business dealings, and somehow that is the form that stuck with us, his American descendants.
During medieval times, the name was pronounced Pon'-dest, with a Norman French accent, of course. Today, in the Isle of Jersey, it is pronounced Pon-chess-ter or Pon-des-ter, depending which branch you are asking on Jersey. While touring Jersey in 1998, the webmaster found residents of Jersey instantly recognizing and pronouncing my American spelled name as if it was spelled as it is in Jersey. One ticket taker at Gorey Castle informed me that I spelled it wrong!
The Jersey Datestones Project has an example of a marriage stone between Jean Poingdestre and Elizabeth Touzel as seen here and on the Project's web page with a more detailed description.