A reverse dictionary can come in handy when you know the definition, but you can’t think of the word. This happens to me a few times a year. For example: “What do you call a lawman in the 1700’s”
This question came up for my work in progress which is set in the 1700’s. I couldn’t think of anything, except sheriff, which I knew wasn’t right. So I searched for “lawman in the 1700’s.” It listed marshal, warden, ranger, and more. Then the word “constable” came up and I went with it. It fit well with the small village in the story.
It also makes a good thesaurus.