"There is an article by Merklinger that tries to describe features of "bokeh" in quantitative terms. You should be able to turn it up on the web. I think it was originally in _Photo-Techniques_. "
Yes, I've heard off-forum that there was a group of articles on bokeh in the May/June '97 Photo Techniques, which likely brought the term to the west. I'll be tracking it down at the Center for Creative Photography soon...
"Also, be aware that the critical appreciation of the appearance of the out-of-focus part of a photographic image dates at least to the era of soft-focus lenses, long before anyone used the term "bokeh" to describe it."
Quite true, and a good point. I'm sure we'd all be very interested in learning whether there was any near-counterpart to the terminology "bokeh" used then. I've never seen it, but could imagine it's there but forgotten.