What does "dd" stand for?

What does dd stand for? I've always referred to it colloquially as "Disk Destroyer", but what are the "official" words that make up the acronym/command?

According to this link and this link it could be one of the following:

1. It used to stand for 'copy and convert' and was renamed 'dd' because 'cc' was already in use for the C compiler.


2. It is a remnant of 'Job Control Language' program conversion into the 'Job Entry System'.


3. It means 'data destruction'