Earlier quoted context omitted.
For me, the "human-readable" part is key. It's not just that the output is e.g. javascript, but that it is more or less human-readable with about the same organization as the original code. If you implement SKI combinators, or three-address instructions, as functions in javascript, and that's the output of your compiler, I would not call that a transpiler.
Would it still count as a transpiler if it minifies the code at the end? For example, most SCSS workflows I've worked with converert SCSS source code into minified CSS, which is pretty difficult for a human to read. But I think that SCSS => CSS still counts as transpiling.
I would say "yes, but the minimization is an additional step that is not actually a direct part of the transpiling process." :-)
So, a program that does this would not a transpiler by itself, but a program that
- executes a pipeline of which the transpiling is the most important step,
- can also be used as a transpiler by making transpiling the only step in the executed pipeline.