Lecture is a talk given to teach people about a subject, especially in a classroom or auditorium setting. In college, professors give lectures to large groups of students, explaining complex topics while the students take notes. A museum guide might give a lecture about ancient civilizations, or a scientist might lecture at a conference about her latest research.

Lectures are different from conversations or discussions. When someone lectures, they do most of the talking while others mostly listen.

The word also means to scold someone at length about their behavior. When your parent gives you a lecture about leaving your bike in the driveway, they explain in detail why it's a problem and what could happen, often repeating warnings you've heard before. This kind of lecture might include phrases like “How many times do I have to tell you...” Getting lectured feels different from having a conversation because you're expected to listen, not argue back.

A lecturer is someone whose job involves giving lectures, particularly at a university.