This is short for "no dependencies". I think a lot of software's ills stem from people's short-sighted tendency to promiscuously add dependencies. In fact, our fundamental metaphor of libraries is wrong. Adding a library to your program isn't like plugging a new block into your Lego set. It's like hiring a new plumber. You're not just adding a few lines of code to a file somewhere, you're creating a relationship. Everytime I see someone talk about "code smells", I wait to see if they'll bring up having too many dependencies. Usually they don't, and I tune them out. And the solution is easy. When you find a library that does something useful, consider copying it into your project. That insulates you from breaking changes upstream, and frees up upstream to try incompatible changes. As a further salubrious effect, it encourages you to hack on the library and tune it to your purposes. (Without giving up the options of merging further changes from them, or submitting patches upstream.)
More broadly, Mu is suffused with this ethos. My goal is that if you have a supported platform you should be able to run it with three commands:
$ git clone https://github.com/akkartik/mu
$ cd mu
(That highlights another benefit: your software becomes easier for others to try out. Without giving out binaries, because what's the point of being open-source if you do that?)
Mu's also geared to spread this idea. I want to build an entire software stack in which any part is comprehensible to any programmer with an afternoon to spare (http://akkartik.name/about). Which requires having as little code as possible, because every new dependency is a source of complexity if you're building for readers rather than users. In chasing this goal I'm very inspired by OpenBSD for this purpose. It's the only OS I know that allows me to recompile the entire kernel and userland in 2 commands (https://github.com/akkartik/mu/wiki/Building-OpenBSD-on-Open...). People should be doing this more often! I think I'm going to give up Mu and build my next project atop OpenBSD. But that's been slow going.
The Pike maxim "A little copying is better than a little dependency" comes to mind. I think the overhead of dependencies is underrated ("it's just a 1 line import statement!"), and often a little repetition is a good thing.