The speaker at today's lecture is a famous author.
Specifically a teaching position at a university or college, often below professor rank.
She works as an English lecturer at a university.
part-time teacher
Refers to a part-time or adjunct teaching role, often in schools or language institutes.
I work as a part-time teacher at a Japanese language school.
tutor; cram school teacher
Typically used for instructors at private cram schools (juku) or tutoring centers.
Cram school tutors provide instruction tailored to each student.
He works as a lecturer at a university.
We invited a famous speaker to the seminar.
She teaches English as an instructor.
The school asked an expert to be a guest speaker.
lecturer on demand; guest speaker on demand
university lecturer; college lecturer