O.Fernandez, thanks for that, it's the most comprehensive and clearest summary I've seen.
In answer to mono's question, isn't bokeh *just* 'out of focus' areas. We perceive this differently, in terms of what is aesthetically acceptable or not (so it's subjective). But an attempt has been made to define certain kinds or patterns of renditions in the out of focus areas.

I think part of the problem of understanding/defining bokeh is a cultural one, and in our western way we want something definite and *right* or *wrong* when it's not as cut and dried as that, and the Japanese language is infinitely more subtle than ours. In the end, it doesn't matter, go with what pleases you. If you think of 'bokeh' as meaning 'blur' (which I think is how it translates) then you realise it isn't specific, and it isn't in itself value-laden, though we make judgements about particular renditions of it.