(n.) a liar, an untrustworthy swindler
Everyone knows what onomatopoeia is, of course, but few people realise that there’s a lot more of it in the dictionary besides snap, crackle and pop. From pebbles to laughter to borborygmi, quite a few words are believed to have been coined in an attempt to echo the sounds they relate to, some of which much more surprising than others. And at probably the most surprising end of the scale is the word charlatan.
Nowadays, charlatan is used in a fairly general way, to mean simply a liar or deceiver. But when it first appeared in the language in the early 1600s, its meaning was a little more precise.
At this point, we can squarely hand things over to the Oxford English Dictionary, as their definition of the original charlatan—written in 1889, when the OED was in its relative infancy—is better than anything we could possibly come up with:
A mountebank or Cheap Jack who descants volubly to a crowd in the street; esp. an itinerant vendor of medicines who thus puffs his “science” and drugs.
The original charlatan, then, was a quack doctor or pedlar of questionable medicines, who would stand before a suitably credulous audience and convince them—with considerably impressive blather or ‘puffery’—of the efficacy of his miracle cures.
But how does that make charlatan an example of an onomatopoeic word?
Charlatan was borrowed into English from French, but French in turn took it from Italian. There, its roots lie in the Italian verb ciarla, meaning ‘to chatter’ or ‘prattle’—and just like the words chatter and prattle in English, the Italian ciarla is meant to imitate onomatopoeically the sound of gabbling, blathering talk. The first charlatan, ultimately, was someone who literally ‘chattered’ while trying to sell their questionable wares, and from there the word has steadily broadened over time to mean simply ‘liar’ or ‘deceiver’ today.