Meaning of “teacher” - Learner’s Dictionary

teacher

noun [ C ] us uk /ˈtiːtʃər/
A drama teacher at school had inspired Sam to become an actor.Until recently he worked as a teacher.The teacher said she was pleased with my work.The teacher is alleged to have hit a student.He felt that his teachers did not give him a fair hearing.

A1 someone whose job is to teach in a school, college, etc:

a history/science teacher

(Definition of “teacher” from the Cambridge Learner’s Dictionary © Cambridge University Press)