The Ken Rockwell article is pretty good, but "bokeh" isn't just about specular highlights.

Another distracting feature can be double lines in the out-of-focus area. Long before anyone used the term "bokeh" in photography, the Wollensak advertised the Verito as a lens that did not create distracting double lines in the out-of-focus area.

There is also the "plastic" (in the positive sense) "three-dimensional" look that occurs when there is a sharp separation between the in-focus and the out-of-focus area, that is a sign of good bokeh. Heliars are particularly known for this effect.