course; lecture series
A series of lectures or classes on a particular subject, often offered by an educational institution or as a public program.
I'm taking a Japanese history course at university.
This course consists of ten sessions and is aimed at beginners.
academic unit; chair
Refers to an organizational unit within a university, such as a department or a chair, typically consisting of a professor and associated lecturers.
He belongs to the Japanese literature chair in the Faculty of Letters.
I'm taking an English course.
The university opened a new course.
I go to a cooking course on weekends.
Professor Tanaka is in charge of this course.
I took the course online.
講義 refers to a single lecture session, whereas 講座 refers to the whole course or the academic unit offering it.
授業 is the everyday word for a regular school class, while 講座 suggests a more formal, often optional or specialized course.
講座 is a lecture series or academic/cultural course, whereas 講習 stresses hands-on practical skill training.
講座 refers to a formal course or series of lectures, while レッスン usually means a single, often one-on-one, practice session.
口座 (a bank account) and 講座 (a course or lecture series) are pronounced identically but refer to completely unrelated things.
From 講 (lecture, explanation) + 座 (seat, gathering place). The combination originally referred to a place where lectures were given, later extended to the lecture series itself and the academic unit.