The word "lecture" first appeared in the late 14th century in modern Latin. The meaning at that time was in reference to the act of reading aloud from a piece of work. Today, it is much more than just speaking to your audience. It involves your body language and facial expressions, along with eye contact with your audience.
In Greek, the word for lecture is "legein," which was originally seen in Homer's work. The meaning for the Greek word is the act of speaking or saying rather than reading aloud as in modern Latin. Books were rare during the time of Homer, so to educate yourself you listened rather than read.
In the 1530s, lecture took on the present-day meaning of the word: a discussion of a topic in front of an audience in order to educate or instruct. Schools continue to use this process to teach their students. The instructor holds to the original meaning by interpreting the text to his audience.