perplexed
Very confused and unsure because something does not make sense.
Perplexed means confused and uncertain about what to think or do, especially when something doesn't make sense or when you're facing a puzzling situation. When you're perplexed, you might furrow your brow, scratch your head, or stare at something, trying to figure it out.
Imagine opening your math homework and finding a problem using symbols you've never seen before. You read it again, check your notes, and still can't understand what it's asking. That feeling of being stuck and confused is being perplexed. Or picture your friend suddenly acting cold toward you for no reason you can understand. You'd feel perplexed, wondering what happened and what you should do.
Perplexed is stronger than just confused. When you're confused about which book to read next, that's a simple uncertainty. When you're perplexed, something genuinely puzzles you or seems contradictory. A detective might feel perplexed by clues that don't fit together. A scientist might be perplexed by experimental results that contradict everything she expected.