To fixate means to focus on something so intensely that you can't seem to think about anything else. When you fixate on a problem, your mind keeps circling back to it like a song stuck on repeat. A student might fixate on a single wrong answer on a test, replaying it over and over instead of moving on. A detective might fixate on one clue, convinced it holds the key to solving the mystery.

The word often suggests an unhealthy or excessive focus. If you make a mistake during your piano recital and then fixate on it for days, you're dwelling on it too much rather than learning from it and moving forward. Someone might fixate on getting the highest score in a video game, playing for hours while ignoring homework, chores, and friends.

While concentration and focus are good, fixation (the noun form) suggests being stuck. The difference is control. You can choose to concentrate on your math homework, but when you fixate on whether someone's mad at you, your thoughts keep returning there even when you try to think about something else.