ullage provided for us one of our more prolonged, argumentative and, ultimately, empty threads.

-joe (well-defined) friday

I remember it well, esp. Dr. Bill's vehemence on the subject. I'm so glad he found us in the last years of his life.
Since we had the thread you referred to, I've seen various TV programs that referred to the space left between the top of a liquid and its container; but not one of them used this word!