I have a problem- I was born, raised and early-educated in Brooklyn. I, to this day, do not pronounce many English words correctly. It took me years to realize that the alphabet includes the letter "R" and that "th" is not pronounced as "D"! I have to take elocution lessons. I still need to work on my English pronunciation so as for Japanese- FORGETABOUTIT.
I sat through a year of "OPTICS" class and never heard the term "BOKEH". We discussed terms like Depth of Field, Circles of Confusion, and all lens abberations- enough to cause a student to develop mental abberations. It turned out that I actually liked certain aberrations for ethereal effects.
"Bokeh" is just a new buzzword for folks to become preoccupied with. So, you get folks spending big bucks on an f/.95 a lens so they can make a portrait and have the subject's ears become part of the "bokeh"! Or, they buy a certain one because they like the shape of the diaphragm blades for, what else? BOKEH!
All kidding aside, of course, background management is an important part of many kinds of photography and understanding and controlling the depth of field is part of that skill set. There are many other factors that influence the appearance of an out-of-focus background. The relative volume of light, the direction of lighht, various interferences and colour content and reflectance of the background. It seems, however, that so many photograhers shoot portraits, flowers and wildlife as if the subject is standing in front of a mass of obnoxious, super colourful party balloons. The "Bokeh" becomes a distraction!
My Brooklyneses interpretation is words like "blobs, fuzz, rhythms, bubblers smooth, sharp, fog, wash, and many other combinations, concoctions, and permutations of the aforementioned slang.
Attached - The results of Spherical Abberation combined with a shallow depth of field. The lens- A Rodenstock Imagon ought H/Stops- looks like a drain strainer from a sink with multiple adjustable apertures. ISO 100, H/6.3 Electronic flash. Gold Xmas tinsel in the background
Bokah? Who knows!