c. 1300, "written works, literature;" late 14c., "learning from books," from Medieval Latin lectura "a reading," from Latin lectus, past participle of legere "to read," originally "to gather, collect, pick out, choose" (compare elect), from PIE root *leg- (1) "to collect, gather," with derivatives meaning "to speak (to 'pick out words')." To read is, perhaps, etymologically, to "pick out words."
The sense "a reading aloud, action of reading aloud" (either in divine worship or to students) in English emerged early 15c. That of "a discourse on a given subject before an audience for purposes of instruction" is from 1530s. Meaning "admonitory speech given with a view to reproof or correction" is from c. 1600. Lecture-room is from 1793; lecture-hall from 1832. In Greek the words still had the double senses relating to "to speak" and "to gather" (apologos "a story, tale, fable;" elaiologos "an olive gatherer").