A euphemism is a word used to replace another worse-sounding word. For example, 'pass away' for 'die', 'battle fatigue' for 'shell shock', 'PTSD' for 'battle fatigue', often a word created to replace a taboo word.
A dysphemism is a bit of the opposite, a synonym that sounds -worse- than the original, for example, 'boneyard' for 'graveyard'.
But there are other directions to take in creating synonyms. Medicalese tends to euphemize to make things palatable, but often there are medical synonyms where the process seems to be more obfuscation or obscurantism than a euphemism. For example, 'urinate' is a perfectly neutral technical term, but it is not uncommon to see or hear the (exact) synonym 'micturate'. Unless I am misreading, there is no euphemizing going on, just hiding through a more obscure word.
What would the process/describing word be for synonyms that are in another register, colloquial vs. formal (though naturally there is a lot of overlap here with euphemism/dysphemism)?
So what I am looking for are synonyms for euphemism, that go in different directions than just good/bad.