Grammar tip: In English, the word "alumnus" is typically declined as it would be in Latin. Especially amongst academics, I'd say.
So if you're writing for that audience, the appropriate forms of "alumnus" are, I think, as follows [0]:
"alumnus" - One male, or one person of unspecified sex.
"alumna" - One female.
"alumnae" - Multiple females.
"alumni" - Multiple persons whose sex is all male, mixed male/female, or unspecified.
Maybe it's common somewhere else to make those distinctions, but they're not common at McGill.
Think of it this way - let's say you make a grammatical mistake that most people consider a mistake. You shouldn't hide behind the "language evolves" catch-all card... you should to recognize it as a mistake and try to use the correct form.
"Alumni" is plural.
I dispute that. Googling doesn't turn up many examples of official usage of alumni in the singular.
I also disagree with your second claim, which is a projection. When I said "common or not", I meant that frequency in itself does not automatically make something correct, and I gave reasons why in a follow-up comment. I didn't claim that usage was common.
I'm not trying to be difficult, but alumni really is plural. Using alumni as singular is not correct.
My friends don't seem to like when I tell them about proper declension when we're in the stadiō.
(Though, to be fair, the native English word children is in fact a double plural as well. [The -re is plural, thus early/dialectal forms childer "child [pl.]", and then later with a plural -n slapped on top of the already plural word, presumably because the -re plural ending had become somewhat obscure, just as Latin plural endings are for some modern English speakers.] Doesn't make me cringe any less at "alumnis", despite that.)
If you're using it by itself as a noun, it's 2nd declension and the ending changes only based on plurality or case, not the gender of the actual graduate(s)
I agree. When thinking about the use of "proper" English, I find myself conflicted.
One the one hand, I truly believe that languages evolve, and it's silly to put any one particular version of English on a pedestal. That includes the version(s) one might associated with English speakers who are well-educated and/or wealthy.
On the other hand, I was raised to speak "proper" English, because my father believed that it strongly affects others' first impressions of the speaker's intelligence. I think my father was right about that, although I'm still undecided about how much it matters, and whether or not it's a concern worth catering to.
Alternatively, if you're using it by itself as an adjective, obviously it will take the appropriate gender. You don't need an explicit noun if you're happy with an implicit "man", "woman", or "thing".
Same grammar confusion happens with "curriculum" (single) or "curricula" (multiple).
"alumnum" is the correct Latin term for a singular person of undetermined sex.
If you have a more authoritative source of information I'd be grateful for a link.
[0] https://en.wikipedia.org/wiki/Alumnus
[1] https://www.grammarly.com/blog/alumna-alumnae-alumni-alumnus...