I wrote about this when I talked about Koshi. Basically Japanese use the word to mean hips but more specifically the back of the hips, base of the spine.
So when Japanese teachers used to tell my teacher to open his hips he found many didn't understand as they saw the hips conceptually as that bowl or even the sides rather than what was meant.
Once again it's a western concept put over the Japanese and so people struggle with understanding it.
To get the reality to my students I get them practicing the feeling of sitting on a comfortable chair or setee and how that action is where you naturally relax the back of the hips and and lower it. Thus awareness of koshi and the Japanese meaning for hips is gained.
I then give examples of let's say the horse stance and how that is sitting in koshi.
Other methods of how to find the hips.
Great, I will give that a try.