To worry anxiously or be despondent about something or someone, especially at great length and in isolation. I know you're upset about failing your exam, but don't brood over it all weekend. Tom's been brooding over our financial situation ever since he got laid off last month.

To worry, fret, or obsess over someone or something. Quit brooding about that fight you had with your girlfriend and just talk to her already! Recent financial losses have the boss brooding about the future of our small company.