A lecturer was a person who gave lectures, typically at universities (TV: The Pilot, AUDIO: The Marian Conspiracy)
The Twelfth Doctor worked as a lecturer at St Luke's University for at least 50 years. (TV: The Pilot, Knock Knock)
Evelyn Smythe was a lecturer at Sheffield Hallam University before joining the Sixth Doctor as his companion. (AUDIO: The Marian Conspiracy)