Here is an example in the press, with an email from Somasegar, leader of developer division in the past.
https://www.zdnet.com/article/microsoft-splits-up-its-xaml-t...
I was an employee in Windows on the date of that email. I left a few months later. Note that the email itself doesn't say "windev". It says "Windows" a bunch of times.
If I'm stretching this "windev" thing, the domain for a lot of employee accounts (including mine) was NTDEV, that had a longer history afaik, nobody called an org that..
The journalist writes it though, as do many other folks.
I didn't come up with this definition myself.
If I am not mistaken, I can probably even dig some Sinosfky references using it.
I think it was sort of externally derived based on "DevDiv", but as another former MS employee - albeit from DevDiv - I can confirm that "WinDev" is not something that was routinely used inside the company the way "DevDiv" is. Usually it's just "Windows", or "Windows org" if the context is ambiguous.