Praise be ! I have not lost all of my little grey cells, after all. I actually remembered one of today's words from an earlier puzzle. Can't tell you which one, of course, but it means "A buff to gray windblown deposit of fine-grained, calcareous silt or clay" The reason I remembered it, I think, is that it was classed as common. I'd never heard of it before, and I still think it's a highly unusual common word !