idiot –Doing the same thing and expecting a different result.Ralph is an idiot.
idiot –An epithet that describes anyone but you.It is a statistical certainty that there is someone out there in the planet who considers you an idiot. That person doesn’t matter, of course — he’s an idiot.
idiot –A person who occupies a position or opinion opposing your correct one.People who think x are idiots.~ Urban Dictionary, (online, *language and content warning)
idioteia – private life or business, Xenophon, Plato uncouthness, want of education Lucian; and
idioteuo – to be a private person, i. e. to live in retirement, Plato, Xenophon:–of a country, to be of no consideration, Xenophon. II. to practice privately, of a physician, Plato III. to be unpracticed in a thing. From
idiotes – a private person, an individual, II. one in a private station, opposed to one taking part in public affairs, Herodotus, Attic Greek; opposed to strategosa private soldier, Xenophon. 2. a common man, plebeian, Plutarch. 3. as Adj., id- Bios (life) a private station, homely way of life, Plato. III. one who has no professional knowledge, as we say ‘a layman’, Thucydides; opposed to a poet, a prose writer, Plato; [as opposed] to a trained soldier, Thucydides; [as opposed] to a skilled workman, Plato. 2. unpracticed, unskilled in a thing … 3. generally a raw hand, an ignorant, ill-informed man, Demosthenes.
idotikos – of or for a private person private, Herodotus, Attic Greek. II. not done by rules of art, unprofessional, unskillful, rude, Plato:–Adv., … i.e. to neglect gymnastic exercises, Xenophon.
~ Greek-English Lexicon, [Middle] Liddell & Scott
It enters English from the Romance languages. It comes from the Greek with two understandings: 1) a private person as opposed to a public person, or, in other words, someone who is not participating in democracy, either by choice or status; 2) an unskilled or untrained individual incapable of a professional trade–typically, thus, a common man (who could not vote). In Latin, the word is streamlined to mean an uneducated man, an outsider or a lay person (Elementary Latin Dictionary, C T Lewis). By the end of the sixteenth century, “idiot” was a legal designation for someone “deficient in mental or intellectual faculty”, but it was already used thus in the written vernacular English as of 1300 (OED).
The legal definition is a tricky thing. It is always dangerous labeling people as “deficient” before the law, because it usually impedes their legal rights. For example, a speech disorder might make one sound as though he is mentally slower, but it does not necessarily reflect their mental acuity, and in fact might cloud the perception of a person who is perfectly competent. Also, at various times, the criteria has been deliberately discriminatory, assessments based on race, ethnicity or poverty. On the other hand, a definition that can legally protect someone who is not capable of fully understanding the consequences of his actions, someone who requires special care and someone who needs reasonable societal accommodations (such as sidewalk ramps for wheel chairs) in order to function, is an important legal designation–and idiot is no longer an appropriate application. Of course, we do not use idiot as a legal definition, anymore, precisely because it is an unscientific definition of someone’s capabilities and denigrates people unfairly and unwisely.
The Romans, whose government was a more limited republic than Athenian democracy (and which also governed a much larger territory and population than that of Athens), largely abandoned the private, as opposed to public, connotation. Personally, I think this is its most valid modern application today: an idiot is a person who chooses not to pay attention to public life–that is, the government’s actions and the politicians who promote or refute those actions. As such, I guess it would make labeling politicians as “idiots” a complete misnomer, but that does not mean that all politicians are smart or competent, just that they are involved–and, not necessarily for the right reasons!