• 係員かかりいん — staff / attendant
• 関係かんけい — relation / connection
• 係長かかりちょう — section chief
• 係数けいすう — coefficient (math)
• 係争けいそう — dispute, controversy, litigation

The character combines the radical 人 (person) with 系 (connection, lineage). It suggests a person who is connected to or responsible for something. Used widely in social and administrative contexts.