(n.) a word or phrase that looks incorrect, but is actually entirely grammatically sound
None of these is right. Between you and me. Both arguably examples of a soloecophanes: a word, or turn of phrase, that looks incorrect, but is actually perfectly grammatically sound.
When it comes to language, of course, labelling things as ‘correct’ and ‘incorrect’ is itself—er, incorrect. But that’s another issue for another day. What matters here is this word, and where it comes from. Or rather, from where it comes.
If you know the word solecism, you’re already on the right etymological track. A solecism is a grammatical error or, more loosely, something written or said that just doesn’t quite add up. Sometimes (and especially in literary contexts) the word solecism is used more specifically to describe a deliberate grammatical mistake employed for rhetorical effect. So that song Is You Is, Or Is You Ain’t My Baby? is a rhetorical solecism—a deliberately grammatically incorrect statement. But more often than not, a solecism is just a spoken or written mistake of any kind.
Etymologically, solecism is one of those words that comes from a place name: Soloi was a Greek colony in Cilicia, an ancient region now on the south coast of Turkey. Living in relative isolation from the rest of Greece, the local Greek-speaking population in Soloi seemingly developed quite a strong regional accent, and their spoken Greek was apparently riddled with all kinds of local quirks and idiosyncrasies. All regions have their own accents and quirks, of course, but those of the Soloi were more striking than most, it seems.
How do we know that? Well, there was a word in Ancient Greek—soloikos—that was essentially used to mean “speaking Greek poorly”, or “using lots of provincialisms in your language”. But literally, it means “speaking like you come from Soloi”. To the more cosmopolitan and somewhat snooty Athenians back on the Greek mainland, the people of Soloi were basically the country bumpkins of Ancient Greece, who spoke with weird out-of-town accents, littered with bizarre out-of-town words and inflections, and who repeatedly fumbled their grammar because they were so unlearned and unsophisticated. Our word solecism, ultimately, derives from this fairly shady Athenian slur. And our word soloecophanes derives from precisely the same root.
The “–phanes” part of soloecophanes comes from another Greek word, phaein, meaning “to show”, or in some contexts, “to look, or appear as”. It’s a root that doesn’t show up much in English today outside of biochemistry and mineralogy. Weirdly, this is the same –phane that you find in cellophane, which was so named because it’s made from cellulose. And it’s the same root at the end of tryptophan, the amino acid that makes you fall asleep after eating turkey. (One for fans of Seinfeld there.) As for the “trypto” part of that? It comes from a Greek root meaning “to rub”, because its enzyme, tripsin, was first discovered when a dissected pancreas was rubbed with glycerin. (One for fans of—I don’t know, rubbing bodily organs with polyol compounds, I guess?)
Other than chemical names, phaein crops up in a clutch of obscure words like calophantic (“feigning a show of excellence”), heautophany (a self manifestation), and heirophant (someone tasked with revealing ancient and arcane theological mysteries). The Greek–Assyrian satirist Lucian wrote a famous essay called Lexiphanes, and its title has come to be used of a peddling word-monger—someone who uses showy, bombastic language just to show off or confuse people. And, of course, this root pops up in soloecophanes: a word or phrase that looks like a solecism, but is in fact entirely correct.