lecture (n.)
A lecture is a talk given in order to teach something. The word comes from the Medieval Latin lectura, a reading, from legere, to read.12
It meant that literally. In the medieval university the teacher read out of the book and the students wrote it down, because there was one book, it was expensive, and they did not have it.1
The sense of a discourse on a subject, rather than a reading out of a text, appears in the 1530s. Printing had been at work for two generations by then.1
A lecture is now an exposition, and often anything but a reading. The word still names the older arrangement: a room with one copy of the book in it.12
The lecture was at nine on Monday.