Bill: For a long, long time, thickness in English referred to Japanese atsumi (厚味). The difference between thick and heavy and the difference between thin and light are difficult for amateurs (both Western and Oriental) to grasp, but most amateur dan players have a pretty good understanding.
A few years ago the editors of the go magazine, Igo (囲碁), brought out a book aimed at high level dan players about playing thickly. John Fairbairn has brought some of the main ideas in the book to English speaking players. One problem for translators is that there is another Japanese word that normally is translated as thickness, atsusa (厚さ).
I do not believe that atsusa is well understood in the West, and maybe not so well understood, even among amateur dan players, in the East. I cannot claim to understand it very well, myself. (I own the book, but I have not read much of it, I am afraid.) And I have a thick style of play! In addition, I have seen examples of usage of atsui (厚い) or atsumi in Japanese go literature that do not seem to me to agree with the usage in the book. (See, for example, Thickness Example 6 and Thickness Example 7.) Maybe that is just my lack of understanding, or maybe it reflects the fuzziness of language.
Anyway, I have mixed feelings about the material on thickness here on SL. I am glad that there is so much about an important concept. At the same time, I am not sure that it is well understood or explained.
Dieter: We've had similar discussions on other pages. From my recent lessons with Minue I have understood that we struggle not so much with thick versus heavy (that much is clear) as thick versus solid and thick versus influential. My understanding of thickness is constantly shifting. I think the difficulty of understanding the concept goes right to the root of Western vs Eastern thinking: static versus dynamic' concepts, the accomplished versus the ephemere.
Bill: Western thinking is static? You don't come from the Wild West, do you? ;)
Dieter: I'm a wanderer, a rolling stone. I may get there in due time.