>1 Not mixed or adulterated with any other substance or material.

You could argue the definitions of mixed or adulterated if you'd like.

>Pure or ultrapure simply mean different and very clearly defined levels of purity for every field they are used in.

Not so clear in the case of dictionaries.

>Please don't try to redefine it.

Maybe fields that use such highly context-dependent definitions of common words should take a look at their wider usages and determine if an update of their nomenclature is appropriate.