We all know Tardis is an acronym for Time And Relative Dimension(s) In Space and there have been rumours that Idris is linked to the Tardis so perhaps Idris stands for something.

Inaccessible
Dimension
Remotely
In
Space?

I Don't Recall It Sorry!

There was a teaser on SFX that says

Isn't Dat Rani I See?

So I could be on the right track.....

Intelligently Disguised River in Secret?

I Detect Regenerated Into Susan

I Don't Really Imagine So.

Spoiler!

Idris Doctors Relative In Space

I like this one

I Doubt Regrettably Its Significance.

Indestructible Dalek Resurrected In Silence

I
Dont
Really
Intelligent
Supposition

I was going to post a thread on this a while back but haven't been home for a bit.

I had it down to either be a female name derived from Tardis or an accronym like Tardis

Internal
Dimensionising
Rift
In
Space

P.S. Dont know if Dimensionising is even a word...hence why I didn't post lol..

Dont know if they will go down this route due to the whole Dr YANA (You are not alone) thing, no idea why just dont think they'll do it twice.

Anagram for Dr II's ??

or would they go for in the same style as the Star Trek 1 movie where VGER = V***GER (VOYAGER)

I.D. RI*** S*** ?

IDRIS =

I
Do
Read
Inside
Spoilers

I do realise it's speculation.

I daresay reality is sillier.

I Don’t Read Irritating Spoilers

Psychics are so scary - (think about it).

If Doctor Reads, I'm Sorry - I Did Rose In School

The Doctor's most secret thoughts revealed:

I
Declare
Riled
Indignation
Smut!

I Do Really Interesting Sex

It Does Recursion. It's Simple:

I'm
Doctor
River
I'm Doctor River IDRIS Song
Song