noun: one making false claim to having a certain expertise; a fraud or a quack.
From French charlatan, from Italian ciarlatano, from cerretano (an inhabitant of Cerreto). Cerreto is a village in Umbria, Italy, once known for its quacks. Another etymology pins the origin of the term on the Italian ciarlare (to chatter), of imitative origin. Perhaps the word charlatan is a blend of the two, as charlatans are known for chattering.
Earliest documented use: 1607
Usage (from Wordsmith)
“Yet despite his career as a space pitchman, Wernher von Braun was no charlatan, and Neufeld shows clearly that his achievements as a rocketman are unsurpassed.”
Guy Gugliotta; Wernher von Braun, Scientist Without a Moral Compass; Washington Post; Sep 16, 2007.