That one really needs to go away from the list; I refuse to accept "figuratively" as a valid definition for "literally", and will contradict / argue with / make fun of anyone who does so.
> 1769 F. Brooke *Hist. Emily Montague* IV. ccxvii. 83 "He is a fortunate man to be introduced to such a party of fine women at his arrival; it is literally to feed among the lilies."
> 1801 *Spirit of Farmers' Museum* 262 "He is, literally, made up of marechal powder, cravat, and bootees."
> 1825 J. Denniston *Legends Galloway* 99 "Lady Kirkclaugh, who, literally worn to a shadow, died of a broken heart."
> 1863 F. A. Kemble *Jrnl. Resid. Georgian Plantation* 105 "For the last four years..I literally coined money."
> 1876 ‘M. Twain’ *Adventures Tom Sawyer* ii. 20 "And when the middle of the afternoon came, from being a poor poverty-stricken boy in the morning, Tom was literally rolling in wealth."
Its meaning in those is closer to "pretty much", "as good as", or "almost like". It's more of a metaphorical intensifier, but there's clearly a metaphor being implied.
They look the same to me.
I think the correct understanding is as hyperbolic use of the regular sense of literally.
If I say, "I walked miles around the store looking for you" or "I waited for you for days", we don't say "sometimes miles means hundreds of feet and sometimes days means a few minutes". We say people sometimes exaggerate.
In the same way, "Tom was rolling in wealth [so much so that it's almost as if he were literally rolling in wealth, but of course that interpretation is silly and I'm using hyperbole to exaggerate how rolling-in-wealth Tom was]".
As you say, you can engage in hyperbole without marking it.
If I say "I figuratively am going to kill him", you're highlighting the figurativeness of the act. You're stressing that you're not actually going to kill him. The meaning of the sentence is "I'm going to kill him... but not really".
If I say "I'm going to kill him" or "I'm literally going to kill him", which mean basically the same thing, it's still implied to be metaphor. But what's being stressed here is the closeness to the metaphor becoming actually literal. The meaning of the sentence is "I'm SO angry with him that I'm ALMOST at the point of killing him".
It's subtle, but there's definitely a distinction. "Figuratively" is a dehyperbolization (it's not really gonna happen), "literally" is a hyperbolization (it is hyperbolically really close to happening).
"Literally" is being used for hyperbole. It makes the sentence more intense.
The word "figuratively" is not used for hyperbole. It's not a synonym. The sentence being figurative does not matter.
That's not a definition of "figuratively".
Think about which way you want the language to be, and then use your vote.
You may not like my swapping the definitions of those words, but that is language how literally works. Therefore, according to your logic, it is valid.
The 'well constructed writing' portion was not specified. What was specified is that someone will make fun of anyone for the colloquial use case.
When someone says "I was so cross I literally exploded!" they are not explicitly pointing out that they didn't really explode, they're just using the word for some kind of emphasis.
A better, similar example could be "I was so ashamed I literally imploded". In this case "literally" is just emphasizing a figurative implosion.
I think "emphasis" is really what this alternate usage is.
I had a weird experience when I rented the tux for my wedding. The tux came with a colored handkerchief that was meant to be tucked into the pocket of the coat in a decorative way; and the guy showing me how to do it kept using "literally": "Literally take the handercheif, and literally fold it over so, and literally put it in the pocket so."
I was a bit bemused, but I didn't say anything, because he was literally taking the handkerchief, folding it over, and so on. But it seemed a bit strange to use it that way; I would certainly never have interpreted him as saying to metaphorically fold the handkerchief, so why emphasize "literally"?
I posted the experience to FB, and someone pointed out that he was simply using the word "literally" for emphasis: in this case, emphasizing how simple the steps were.
When people say things like "My head literally exploded", they're doing the same thing: simply using it as an intensifier.
The insistence that simple emphasis is a valid use for "literally" -- and quoting M-W or the OED to support your case -- is just as prescriptive the insistence that it doesn't.
Language is socially constructed by the people using it; we all "vote" by using it, and by policing its use.
So let me ask you this: Do you want "literally" to be a meaningless emphasis word (and thus lose its ability to specify "this actually happened")? Or do you want "literally" to mean "I am not speaking figuratively, this thing actually happened"?
If you want the former, then I disagree with you, but sure, go ahead and use your "vote" to police people objecting to "literally" meaning "figuratively". But if you want the latter, then join me in insisting that it means "this actually happened".