For a large part, this can work. But there are several cases where it doesn't. Modules, subdirectories, a group of classes, etc. Too often, at least a part of the terms don't have a logical place to go in code. I consider it worse to have them partly here and partly there, than to have them all together.

But, indeed, I often repeat the definition or naming in the class documentation, module file, methods etc. Knowing fully well it will drift, but accepting it does. And everyone knows the canonical place is dictionary.md, inline docs are merely reminders or copies of that canonical place.