A quick look at the meaning of "voll" and why "voll leer" actually makes sense in colloquial German.
voll, machtvoll, liebevoll, sinnvoll, komplett
The original idea of this family was:
And it could be a liquid as well as a flowing motion in the air.
Here’s an (incomplete) list of English members of the family. You’ll see that most of them are about a “continuous motion” in or of liquid or in air.
- pulmonary (Originally: the body part that floats)