Archaic or highly literary term for a lecture hall or a lecture itself. In modern Japanese, 講堂 (こうどう) or 講義室 (こうぎしつ) are used for the room, and 講義 (こうぎ) or 講演 (こうえん) for the lecture.
In old texts, it is sometimes used as in 'to attend a lecture' (literally, 'to sit in the lecture room').
Compound of 講 (lecture, discourse) and 筵 (mat, seat). Originally referred to a mat or seating area for a lecture, then extended to the lecture itself. The exact historical derivation is uncertain; the spelling is conventionally associated with these meanings.