Demonyms
 

A very simple question (well, two questions...well, two and a related third).

Why is it Gondorians instead of Gondorrim?

Similarly, why is it Numenorians instead of Numenorrim?

I initially thought it was to avoid being pejorative (i.e. Haradrim) but the greatest allies of Gondor were the Rohirrim, so that might not be the case...at least not directly.

Perhaps it was still a bit of cultural pretension of "-rim" not being used to describe directly Edainic peoples (I say "directly" because the Rohirrim were of ultimate Edainic extraction).

A related question would be...Elves did not generally seem to have "national" demonyms for themselves, at least to my recollection. What would an Elf of Nargothrond have called himself, if anything?

Never thought about it. Could it have something to do with the Common Tongue, where the "-rim" ending is only kept as an exception, in imitation of Elvish (or at least the Gondorian dialect)? Perhaps it was Gondorrim and Numenorrim when spoken in their language.

I would guess that it's just a case of the suffixes -han, -rad, and -dor simply being conjuncted (?) differently.

We do this in English:

Scotland = Scottish
England = English
Ireland = Irish

Japan = Japanese
Portugal = Portuguese
Taiwan = Taiwanese

Russia = Russian
Lithuania = Lithuanian
Bulgaria = Bulgarian

Because it's English, and English is essentially a square peg of French hammered into a round hole of German, it isn't always consistent. But, I think it's the same idea.

Because Tolkien wrote it that way
 

One answer to your question, Kuruharan, ones that's a little tongue in cheek, :p is that it's because Tolkien wrote things that way.

For example, he wrote 'Middle-earth', not 'Middle Earth'; so we and other fans who write about him and his works tend to write that title according to the first example, with the dash. ;)

You asked a good question, and Galadriel55 and Andsigil offered some good answers.