The Dragon God of Time goes by so many names.

So, why does Paarthurnax choose "Akatosh" to refer to him when speaking to the Dragonborn?

This is even more curious because we're not talking about cultures and races here.

As a dragon, he was directly created by the God of Time and has strong ties to him.

I don't know. Maybe because we are in Skyrim, and he figured that would be his most recognized name around these parts?

Maybe that's his favorite one?

Maybe he didn't think about it?

eh, maybe because the Nords would recognize Akatosh by that name the most?

I doubt Bethesda would put the amount of depth for Paarthurnax to refer to him by Alkosh if he was talking to a Khajiit Dragonborn.

Paarthunax doesn't care about petty semantics. Akatosh is what the Dovahkiin knows the god as so Paarthunax calls him Akatosh to get his point easier across.

How would he come to that conclusion?

Bethesda gave him some inside info.

I don't think it really matters to him for this reason: "A rose by any other name is just as sweet." It's a shame I don't really like that play though..or roses.

Because Our character would be confused by Bormahu. Akatosh is the most common name for the Time God in Tamriel.

Who, Paarthunax? He has the Greybeards to keep him up-to-date about the matters of the world.

I'd personally go with this, and I'm sure the Greybeards keep him up to date on mortal matters if anyone wonders why.

First time that I've ever been ninja'd on the forums.

Either he means the oversoul and "first born of Akatosh!" means that he is the first aspect of Aka to form. Which makes sense given his role.

Or he references mannish Akatosh specifically because Akatosh was broken and placed at the very beginning of creation, making him responsible for Alduin's existence. Now he in council with Shor bless the LDB to rid of this project gone wrong (that may have never been intended in the first place?)

I think its the simple fact thats the name the PC would most likely recognize than his other names I don't think its something really complicated.

The Greybeards aren't even up-to-date with the matters of the world, so it must be difficult for them to keep Paarthurnax updated.

@OP: Paarthurnax uses Akatosh because it is more recognisable [to players] than Bormahu.

During Season Unending they seem to be pretty well aware of the situation in Skyrim.

"His Coolness" doesn't need to be kept up to date.

The guy's pretty much omniscient in my book !!

Well, I mean, they rely on pilgrims climbing the 7000 steps for their information. Few pilgrims it seem ever go that high and even whats-his-face in Ivarstead generally doesn't talk to the Greybeards.