The word "lecture" is used when someone speaks about a topic or a subject at great length. Teachers and professors lecture, but a lecture can also come from a person in a position of authority, such as a parent or a police officer.
A police officer pulled over the car and lectured the driver on the importance of safe driving. (This sentence uses "lecture" as a verb.)
The police officer gave the driver a lecture. (This sentence uses "lecture" as a noun.)
John’s father gave him a lecture on being a responsible person.
He lectured his son.
Our professor’s lectures are so interesting that many students record them and listen to them later.
This lecture hall holds over 200 people. (This sentence uses "lecture" as an adjective.)
The teacher’s lecture on Hamlet seemed to go on forever. It was so boring.
Lectures found on TED are very popular. You can listen to and learn from the world’s greatest thinkers on that website.
Tina got upset when her husband tried to lecture her on how to be a good wife.
Note: Pay attention to the pronunciation of this word. The "t" in "lecture" is an "sh" sound: /lekshur/