Concerned means worried or troubled about something that matters to you. When you're concerned about a friend who seems sad, you notice something's wrong and care enough to think about it. When a teacher is concerned about your grades, she's worried they might be slipping and wants to help before things get worse.

Being concerned is different from casual worry. It means you're paying real attention to something important. A parent might be concerned about their child's cough that won't go away, or a student might be concerned about finishing a big project on time. The word suggests both care and a sense that action might be needed.

You'll also see concerned used to mean “involved with” or “related to,” as in “the people concerned with planning the school assembly” (the ones working on it) or “as far as homework is concerned” (when it comes to homework).

When someone says “I'm concerned that...” they're expressing something stronger than a passing thought. They've noticed a real problem and think it deserves attention. A concerned look on someone's face tells you they're thinking seriously about something that's troubling them.