This is the 2222nd most frequent Japanese word.
系列
"Series," "system," or "group of related things."
In this context, '系列' refers to a specialized field or branch within an institution or organization.
この大学は古典文学研究の系列があります。
This university has departments for classical literature studies.
Here, '系列' is used to denote a network or sequence of shops under the same management or brand.
彼はその会社の系列店舗をいくつか訪れました。
He visited several chain stores of that company.
In this case, '系列' references the branches or subdivisions of a particular field of study or interest.