'Folklore has it that when Carl Jung was once asked which was the correct spelling—ExtrAvert or ExtrOvert—Jung's secretary wrote back something like, "Dr. Jung says it's ExtrAverted, because ExtrOverted is just bad latin."'
[...]
'According to the Oxford English Dictionary, "The original spelling 'Extravert' is now rare in general use but is found in technical use in psychology." That's correct. If you look at scientific journal articles, virtually every paper uses the spelling ExtrAvert.'
In English, spelling is so seemingly arbitrary at times that I just gave up and quit caring so much. Judgment? Judgement? Who cares?! I won't budge on my thoughts on the importance of proper grammar though.
Grammar pedants are the worst. It generally isn't very important if people understand what is being said. There are a few edge cases, but in general its pretty obvious.
In this case I (en-gb native) initially thought extravert was some tertiary alternative to extrovert and introvert; then assumed it was errant/en-us spelling.
I'd think of extro- and intro- as looking out and in respectively. Extra- and intra- would be externally additive and internally additive; like a connection outside a defined group and inside such a group respectively.
It's been pointed out to me lately that "prescriptive grammar" is apparently classist/racist, which is strange considering I grew up dirt poor in Appalachia but still bothered to learn the difference in "who" and "whom". In languages like French it's a crucial understanding but English got lazy and for whatever reason, direct object pronouns are a tripping point for many students of a foreign language. Astounding.
Yes, intro- is a Latin prefix meaning "to the inside" while extra- means "to the outside". The "-vert" is from the Latin verb "vertere", meaning "to turn".
Adding Latin prefixes to "vertere" leads to such words as "to avert" (a- from Latin "ab-", meaning "from"), "to evert" (from "ex-" which means "out"; compare "extra-" above), "to invert" (from "in-" meaning "into"; compare "intro-" above); "reverse" (an adjective meaning 'opposite' from "re-" meaning "back"); "transverse" (an adjective meaning 'crosswise' from "trans-" meaning "across"); and so forth.
It's useful to compare "in-" vs "intro-" and "ex-" vs "extra-". The "-tra-" and "-tro-" infixes are essentially the same, but Latin writers and speakers inflected them historically. English inherited this in such words as "introduction", "extradition", "introspection", "extraordinary", and "extravagant".
Finally in modern biological and medicinal jargon it is common to use "intra-" (with an "a") as "within": "intracellular" (within cells; compare with "intercellular", "between cells"), "intradural" (within the dura mater in the spinal cord), "intramolecular" (e.g. internal forces holding together the shape of a molecule, or the atoms a molecule comprises), and so forth. Outside those technical settings, "intra-" is exceedingly rare. One example is "intramural" ("within the walls", usually used to describe a competition between different teams of students at a single school, however the word has use in medicine as well, the walls being those of a cell, blood vessel, or other hollow organ, and the medical use likely came first).
But the author of this post goes even further, and uses both spellings in the same sentence!
In extravert-introvert pairs, extroverts report on greater closeness than introverts
That can't be right...