From Sara Ahmed:
The experience of this process offers us the opportunity to “thicken” our description of institutions. The philosopher Gilbert Ryle suggests that “thicker descriptions” require more than describing an action; it would locate an individual action in terms of its wider meaning or accomplishment. He suggests that a thin description of what a person is doing (such as doodling) requires thickening “before it amounts to an account of what the person is trying to accomplish.” (Ryle 1971: 498)
The idea that the path to an understanding might not follow the orderly categories of some expert’s discipline, but rather a patient method of observation and annotation leading to something that might be as much an account as it is an analysis. A story told by someone who didn’t rush to commence the tale, but who held back, observing and reflecting.
I’d better look up some other discussions of the term, at least in the field of anthropology. Remember, too, that a half century ago an interesting anthropologist had to cast her research as a novel because the field didn’t have room in its analytical categories for accounts based on something like thick description. So she published Return to Laughter under a pseudonym.