missing words and convoluted sentences
When I was in college and taking German and French conversation courses, there was always the problem of running up against something you didn't know the German or French word for. We were instructed not to hem and haw, or ask what the word was, but to talk around it. The results of taking this advice were often hilarious. Talk about convoluted sentences!! Now that I'm ancient and the little grey cells are becoming exhausted, I find these lapses which you described (which I never used to have) more and more frequent, so I have to resort to the old technique of "talking around it", with what results you can imagine.