lengthy lecture; long talk
Refers to a lecture, speech, or talk that goes on for a long time. Often carries a slightly negative nuance of being too long or tedious.
I'm always fed up with his lengthy lectures.
The participants were bored by the long talk at the meeting.
long talk; lengthy speech
Compound of 長 (long) and 講 (lecture). The exact historical derivation is uncertain, but the meaning is transparent from the kanji.