Is the proper feminine version of “dude” “dudette” or “dudess”?
Going off of my idiolect, it’s dude.
And I will never give up my march to make singular they a thing. The only time I wince is if I write themself but so far no one’s ever mentioned it, so I think I’m getting away with it.
The singluar “they,” in my opinion, is the neatest solution without sounding contrived. I use it all the time in both writing and speech, unless I feel my audience is particularly pedantic.
According to Google, there are some web sites that offer a definition of the word. Google is just a search engine, not a regulatory body.
There is not an official standard of what words are accepted English language words (unless you want to count dictionaries, which aren’t standardized or regulated either). Unofficially, if you speak and the person you are talking to understands you, then your usage, grammar, pronounciation, etc, are “accepted”. The other persons ability to understand your speech may vary in different parts of the country or even from person to person.
“Principle of common usage” is what makes words accepted or not accepted in English. In other words, if enough people use a new word, or a new meaning or pronounciation of an existing word, then it becomes commonly accepted as part of the language. For example the word “Forte”, when used to mean area of expertise, was correctly pronounced “Fort”. But so many people mis-pronounce it “Fort-ay” that the newer usage is becoming accepted as correct. That’s how languages evolve.
That said, I kind of laugh at people who attempt to introduce “gender-neutral” pronouns into the language, and I don’t think any of them have been even remotely successful outside of small groups. If I’m referring to someone whose gender I don’t know, I will use “they” or “their” in place of “him/her” and “his/hers”. I don’t feel a screaming need to have gender-neutral pronouns in our language other than that, and from the lack of them (outside of a few small groups), I don’t think many other people do either.
Finally, I’ve never heard anyone use “hir” before. But it’s possible that I have and mis-heard it as “her”, as I think they would sound very similar.
I dunno about your dialect but in mine at least, it’s the same vowel sound.
They ignore it. Only online dictionaries that aren’t connected with a traditional book-dictionary include it, which means that it’s certainly not accepted by an overwhelming number of lexicologists and nowhere near common usage.
The use of ‘hir’ and any newly created word for pronouns have historically not been accepted except in small circles.
If you’re looking for gender neutral singular, you can choose from:
[ul]
[li]He/him - the traditional one which, since it doubles as a gendered pronoun, can be problematic at times both for clarity and for lack of bias.[/li][/ul]
[ul]
[li]One - One can use this as often as one likes but it’s overuse can make one’s use of it sound awkward to oneself.[/li][/ul]
[ul]
[li]‘Singular’ they/them - has been used for centuries in English including heavyweight ‘standard’ authors (Shakespeare) and in pop culture (Sting). Since it doubles as the plural pronoun, it can be problematic for lack of clarity at times. Because of the 19th century Latinist prescriptivists who wrongly asserted this usage was incorrect, you may find one who objects to its use, but they need to get over themself.[/li][/ul]
Funny thing about language is, with the exception of most etymologies, almost anything else is opinion. “Hir” is not something I’m likely to use. Nobody I work with knows the term so my use of it would cause confusion, gender neutral singular “they” is accepted in the vernacular and gender can be written around in more formal correspondence (I’m more bold and will typically use gender-neutral he rather than go so far as the clumsy he/she–clarity trumps sensitivity for me, but then I never said I wasn’t an asshole), and frankly it’s a solution to a problem most people don’t recognize.
That’s the only place I’ve ever encountered “hir,” either. It’s not used as a gender-neutral pronoun, it’s a pronoun for hermaphrodites, usually in some sort of sci-fi/fantasy world setting.
I’m a reasonably well read person and this is the first time in my life I’ve read this word. I wold suggest that it is not something an adult would yet use in serious correspondence.
The correct answer to your question is that it’s a real English word if Lexulous allows it.
It’s not official English, yet.
It’s not recorgnized atdictionary.com
Or the Free Dictionary
Or the Cambridge dictionary
You’d think one of them would list it if the word were even generally accepted in academic circles.
For what? 
It is a acronym for the Harvard Int’l Review, yes. It’s the designation for Henderson International Airport , true. A few more. Which are you talking about?
I made a conscious decision awhile back to use ‘she’ and ‘her’ for the gender neutral pronouns.
Why, you may very well ask?
Because I like women more than men, just in general.
And women deserve a break linguistically.
I’ve only ever encountered “hir” in my university’s student newspaper, in one article, which was about one of the writing staff members who didn’t identify as either gender. And in this thread.
Invented gender-neutral pronouns seem to have a tendency to sound utterly asinine to many people. I suspect that it will be a while before we all agree on one.
I’ve used “she or he” and “her or him” for years. It was an easy habit to develop. I’m a little surprised that more people don’t use those variations at least from time to time.
As with hyphenated surnames, “hir” is a reflection of indecisiveness, weakness and linguistic conceit.
I suspect it has a chance to catch on “officially” in the lexicon of those hoping to cast an aura of progressive superiority long before it takes a place in common usage.
Still, predicting what the polloi will latch on to is a pretty inexact science, so maybe a more pervasive use is right around the corner.
I see where you get your username from. 
It’s not generally accepted in academic circles. I don’t even think it’s accepted by all academics in gender or queer studies. It’s used by an extremely small subset of academics, by some transgendered people and some organizations who strive for gender neutrality in language for ideological reasons.
Exactly my response when I read the question. WTF? Hir??? I’m surprised the question is raised because I’ve never even heard of the topic.
Speaking as a transwoman who is very active in a large community, I have never heard it used, ever, and I’m not sure I’ve seen it in writing. I by no means am omniscient, but it must be pretty doggone uncommon.