Qt makes heavy use of the PIMPL idiom in their development process: https://wiki.qt.io/D-Pointer
As I've read here: "The name 'd-pointer' stems from Trolltech's Arnt Gulbrandsen, who first introduced the technique into Qt, making it one of the first C++ GUI libraries to maintain binary compatibility even between bigger release.". But nobody says what "D" stands for.
So what does the "D" stand for in D-Pointer?
From this page Data Sharing with Class (an old docs from QT), it says:
Before we can share an object's private data, we must separate its interface from the private data using an idiom called "d-pointer" (data pointer)
So, d-pointer means data-pointer