I unlinked this from the Russian, which means "rejection" (act of rejecting) rather than "reject" (rejected object, as on a factory assembly line).

The French doesn't match either.
https://www.larousse.fr/diction...is/refus/66806

@felix63, I unlinked the English from the French.

Doesn't this also mean "I regret having to inform you of this, but (after carefully considering your application) I've decided to reject it."?

I would only use "a reject" to refer to something that is inherently defective, not to something or someone that has been rejected after a substantial review. When applied to a person, it's especially insulting. You might hear an obnoxious kid saying something like "You're such a reject. You can't even dress yourself." But someone on a college admissions board would never say this to an applicant, for instance.

Interesting. I've definitely seen people use "reject" in that way.

E.g. student admissions https://www.thestudentroom.co.u...5#post58439529

"Do top universities reject those who are resitting their exams and reapplying?" "It depends what you're applying for. If it's medicine, dentistry or business related then it's a reject."

job applications https://www.teamblind.com/post/...dback-UrxfTaL8

"I had virtual onsite with NVIDIA about 5 days ago but no word yet. Recruiter said generally the candidate is informed in a couple of days. Does this mean it’s a reject?"

I don't think "reject" refers to the applicant in this case, but to the response. Like in "I'm afraid it's a no from me." But maybe only non-natives talk this way.

Within the context of a forum, people often speak more informally and shift words from one part of speech, or sense, to another, without using punctuation (such as quotation marks) to indicate what they're trying to do. In those forum posts, the meaning is clear. But at Tatoeba we're dealing with sentences in isolation. So I don't think that posts from a forum that is largely about acceptance and rejection of applications (so everyone knows what is being discussed) make a good model for what one might call the "context-free context" here. If quotation marks were used, and more context were offered, that might help:

We have looked over your application, and I am afraid we have decided it is a "reject".

Here, putting "reject" in quotes gives you more freedom, as in this sentence, where an adjectival phrase gets treated as a noun phrase:

To me, that's a definite 'totally disgusting'.

But I still much prefer:

I am afraid it is a rejection.
I am afraid it needs to be rejected.
I am afraid it wll be rejected.

depending on what is meant.

Note that the original sentence came from the Tanaka Corpus, which means it may well have been contributed by someone who would have used "rejection" if s/he had known English better.