This is the 293rd most frequent Chinese word.
主任
Director; head; chief.
In this sentence, '主任' means 'principal'—the head of a school.
学校任命他为新校主任。
The school appointed him as the new principal.
In this example, '主任' is used as a formal title for someone in charge, followed by their surname.
李主任正在办公室等待拜访。
Director Li is waiting in the office for the visit.
Here, '主任' stands for 'director,' referring to a position responsible for leading a project or department.