That definition was made after the sense being used in this article (and this sense has been widely used in cybersecurity in general). Your linked term comes from an acronym written on prison cell doors (Not On Normal Courtyard Exercise) while the meaning of "used only once / unique" has an etymology dating back to Middle English.
“Slut” originally means an untidy woman but if you call someone that, a knowledge of etymology is not going to help. Language doesn’t work based on precedent.
I'm not talking about precedent -- the comment was that it was a poor choice of term, implying that the term in the article came about later.. when the uniqueness sense of the word has been in use since long before that.
Though the slang word looks like it originated in '71 and the cybersecurity use of it only goes back to '78, so perhaps it was a poor choice indeed. Though, with its similarity to the use by dictionary editors and cartographers, it makes sense why they would pick that term.
I only today became aware of the pedophilia reference for it and will have a difficult time unthinking thoughts of revulsion whenever I encounter the security-related term, but what can you do.
> Your linked term comes from an acronym written on prison cell doors (Not On Normal Courtyard Exercise)
These are _always_ backronyms. _Always_. If anyone ever tells you that [random word that's been around for a while] is an acronym, they are _wrong_. (Possible notable exception for 'fubar'; that one's old enough now and probably really is an acronym).