The word "charlatan" comes from the Italian charlatano, meaning "quack" or "mountebank", and is related to the verb cialare, "to prate" or "to gabble".  The ultimate origin is Italian, likely a blend of ciarlare ("to chatter") and cerretano ("a native of Cerreto," a town known for quacks).   The word passed into English through the French charlatan and around the early 17th century the word initially referred to a traveling medical quack who used patter and schemes to sell fake remedies.  It later came to describe someone who pretends to have knowledge or skill they don't possess.  

According to the Oxford English Dictionary (OED), the earliest use of the word "charlatan" in English was around 1576, in a work by Arthur Hall. 

Examples of "charlatan" used in a sentence: 
"The fraudulent miracle healer was exposed as a charlatan who had tricked thousands of people out of their savings."  
"Some are charlatans soaking the rubes for a few drachmas." 
"He was exposed as a charlatan after his promised medical cures failed."  
"Beware of charlatans who try to sell you access to the fountain of youth."  
"Many believed the Wizard was a great and powerful wizard, but in reality, he was just a charlatan." 

Just the facts:

CHARLATAN Definition & Meaning - Merriam-Webster

CHARLATAN Synonyms: 55 Similar and Opposite Words | Merriam-Webster Thesaurus