This is the 8907th most frequent Japanese word.
歴任
"Rekini" (歴任) means "to hold successive positions" or "to serve in various posts."
In this sentence, '歴任' is used to indicate that the person occupied various positions in succession within the same role or department.
彼は大学学部長を歴任した。
He has held successive positions as the dean of the university faculty.
Here, '歴任' signifies the succession of responsibilities across different departments, stressing a variety of positions held.
歴任した部署のすべてで高い評価を得た。
In all the departments he successively held leadership of, he received high evaluations.
This usage of '歴任' emphasizes the accumulation of experience over progressively held high-ranking positions.