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.
会議での長講に、参加者はうんざりしていた。
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.