1. Smitten with someone. Oh, he's been stuck on you for years—of course he'll be your date to the dance!

2. Fixated or focused on something, such as an idea, feeling, or belief. A: "Why is Adam mad at you?" B: "I think he's stuck on the fact that I made the track team and he didn't."

3. Unable to make progress past a certain point or level due to something that one is confused by, unable to do, etc. I'm stuck on this part of the instructions—can you explain it to me again? If you get stuck on any one question, just skip it and move on.