Which word describes an employee's group within a company?

The term that best describes an employee's group within a company is "department." A department refers to a specific division within an organization that focuses on a particular function, task, or area of expertise. For instance, a company may have various departments such as marketing, finance, human resources, and operations, each dedicated to performing particular roles and responsibilities that contribute to the overall objectives of the company.

While "team," "personnel," and "staff" can also refer to groups within a workplace, they differ in their definitions. A team generally indicates a subset of individuals collaborating on a specific project or task, which may or may not align with broader departmental structures. Personnel is a more generic term that encompasses all employees within the organization and does not specify a particular group or division. "Staff" is often used to describe the overall workforce of a company but lacks the context of division or specialization that a department provides. Thus, "department" captures the essence of a distinct employee group with its own specific functions within a company.