A person in charge, an assignment of duty, or a position responsible for something — an official or clerk in charge.
受付の係に用件を伝えてください。
Please tell your request to the person in charge at reception.
この係は書類のチェックを担当している。
This section/person is in charge of checking documents.
係員が案内してくれるまでお待ちください。
Please wait until the attendant guides you.
In linguistics: a connection or linking element in sentence structure (kakari — the grammatical linking of elements).
古典文法では係という概念が重要になる。
In classical grammar, the concept of kakari (linking) becomes important.
係り結びのルールを学ぶと文の構造が分かりやすい。
Learning the rules of kakari-musubi makes sentence structure easier to understand.