Etymologically, pari- is cognate with Greek peri (as in perimeter “measuring around”; peripatetic “wandering around”; periphery “carry around”; period, literally “a way around”, by figurative “a [full] cycle” ).
It loosely refers to circles, circling, around, encompassing, completeness. With respect to verbs it can give a sense of action completed or done to the nth degree.
A word like “pure” doesn’t really admit to degrees. Pure is a binary proposition - the slightest impurity means that something is impure. So “completely pure” doesn’t really give us new information, it is a form of literary emphasis to mark this experience as out of the ordinary.
In the case of pariyodāta and parisuddha I would have thought that pari has a superlative sense.
Re: kāya, the basic meaning of the word is “group”. Most authorities take it to come from √ci “to heap up”. It means “body” in the sense of a heap of the four elements. And I think this reminds us of how very alien is the Iron Age worldview in the Pāli texts. One to one correlations with modern ideas about bodies and minds are rare.
My impression is that kāya and cetas are usually distinguished. Except that a term, which seems to be quite late nāma-kāya where kāya takes it’s literal meaning of “group” and refers to the non-rūpa khandhas.
I’m not sure I have come across a context in which kāya could mean “person”. My view is that sakkāya, literally “a group that is existent” is a very strange expression and that semantic approaches to understanding how Buddhists use it are unlikely to be fruitful. When I look at the Pāḷi explanations, they are not semantic explanations, they are just assertions. X means Y, for no reason other than that we say it.
This is true of many technical terms. And it means that taking a semantic approach to translating leads to ambiguity at best. We’re still arguing over how to translate these words after 200 years of Buddhism Studies, which suggests we’re using the wrong methods.
However, look at PTSD p.207. The “psychological” meaning of kāya is that it is the “seat of feeling”. In other words it is where we experience vedanā. This would seem to be related to the idea of withdrawing from contact, because contact is one of the conditions for the arising of vedanā.
I see Buddhists wanting to drag in this concept of “direct” in all kinds of ways. I’m less and less convinced that this works. "So imameva kāyaṃ parisuddhena cetasā pariyodātena pharitvā nisinno hoti;
Kāya doesn’t seem mean “direct” or “person” in this sentence, why should it change to mean that in other sentences in the same context?
What does it mean to kāyaṃ cetasā pharati “Pervade the kāya with the cetas”? It clearly meant something in 400 BC but I don’t have any clear sense of what this means looking back.
Pāli has no category of experience that corresponds to affect or emotion. It has words for emotions, but they are not different from thoughts or feelings. It’s a very different worldview we are dealing with.