The word "ki" is a homonym. I believe (though I'm speculating here) that it's a homonym in Japanese as well as its adopted usage in English. Like all homonyms, the meaning of the word ki is derived from the context in which it is used.
To insist that ki have one and only one correct meaning is like asking what is the one correct meaning of the word "bank". Is a bank a raised ridge or shelf, or is a bank a place where financial transactions are conducted? Obviously a bank is both but the meaning of the word bank can only be known when it is used in a sentence.
Greg and I recently had a side discussion of this topic wherein we each related our views and experiences regarding the nature of ki. Though our views are diametrically opposed, we had an informative,cordial and fruitful discussion because neither of us insisted that the word ki had to conform to one and only one meaning. There was no obscurity or ambiguity because we each clearly defined the value of the content to which our individual use of the word ki referred.
Well, there are a relatively small number of sounds in Japanese - so everything's a homonym to something, in a manner of speaking. OTOH, the kanji for "ki" is specific, as is the usage in certain martially related compounds - you wouldn't mistake if for a bookshelf, for example.