Euphemisms and Forbidden Divine Names

Mississippi Fred had a great post on Samaritans a few days ago. In it, he used the term 'euphemism" to describe the practice of using another word (such as Hashem) for the Tetragrammaton. I had never heard this usage, so I asked him whether that is the right word to use. The only meaning of the word "euphemism" I've encountered was the substitution of an inoffensive word for an offensive word or concept.

However, Fred was insistent that his term was correct, so I set out to do a bit more research. I've checked a few dictionaries and none of them had any other definitions than what what I've known. However, Wikipedia mentioned the following:

The word euphemism comes from the Greek word euphemo, meaning "auspicious/good/fortunate speech/kind" which in turn is derived from the Greek root-words eu (ευ), "good/well" + pheme (φήμη) "speech/speaking". The eupheme was originally a word or phrase used in place of a religious word or phrase that should not be spoken aloud; etymologically, the eupheme is the opposite of the blaspheme (evil-speaking). The primary example of taboo words requiring the use of a euphemism are the unspeakable names for a deity, such as Persephone, Hecate, or Nemesis.
[...]
In some languages of the Pacific, using the name of a deceased chief is taboo. Amongst indigenous Australians, it is forbidden to use the name, image, or audio-visual recording of the deceased, so that the Australian Broadcasting Corporation now publishes a warning to indigenous Australians when using names, images or audio-visual recordings of people who have died.
[...]
In a similar manner, classical Chinese texts were expected to avoid using characters contained within the name of the currently ruling emperor as a sign of respect. In these instances, the relevant ideographs were replaced by homophones. While this practice creates an additional wrinkle for anyone attempting to read or translate texts from the classical period, it does provide a fairly accurate means of dating the documents under consideration.

The one thing that is still a bit vague for me is that even in the sense of the word that means "Substituting another word for a sacred name or phrase that should not be spoken aloud", it seems like there is still the notion that the original name or phrase is evil or demonic and so using it will somehow focus the attention of the evil entity on the invoker of the name. For example, the Greeks would not mention the Furies by name, nor as Wikipedia notes, Hecate and Nemesis. The one thing that was a bit puzzling to me was why Persephone was mentioned in the list. Looking further in Wikipedia revealed the reason:

Of the four deities of Empedocles's elements, it is the name of Persephone alone that is taboo— Nestis is a euphemistic cult title— for the Greeks knew another face of Persephone as well. She was also the terrible [Queen of the Dead], whose name was not safe to speak aloud, who was euphemistically named, simply as, Kore, "The Maiden", a vestige of her archaic role as the deity ruling the underworld.