Sentence:  The point, to her, seemed to be to show that whatever was going on around him was subordinate to the great private productive secret-not-necessarily-related-to-anything-his-<WSD>groundling</WSD>-friends-were-talking-about trains of thought that Douglas was having. 
Meaning of the word marked with <WSD> tags:  A person of uncultivated or uncultured taste.