The most common Korean word for “teacher” is 선생님 (seonsaengnim). There is one more word with a similar meaning — compare them below. 「teacher」는 한국어로 선생님.
teacher
TOPIK 1 · noun
teacher; instructor
TOPIK 2 · noun
Words and levels: TOPIK I essentials (National Institute of Korean Language standard curriculum, KOGL Type 1) · examples: Cheesepotato