Got there eventually (thanks mostly to the LY hint, TBH)! I looked at my existing top words in the mid-to-high 900s and tried them and their opposites with the LY ending, then put the highest ones into thesaurus.com. It was rather a brute force approach, but I think words ending in LY are always going to be tricky, because very different terms can describe the same thing and are thus considered close.