The term that describes a group formed by a master machine and a worker machine in a Kubernetes architecture is "Cluster". A cluster in Kubernetes consists of one or more master machines and multiple worker machines (also known as nodes). The master machine manages the overall control plane and orchestrates the deployment and management of containers on the worker nodes. The worker nodes are responsible for running the containers and executing the workloads. The cluster is the fundamental unit of organization and management in Kubernetes, providing the infrastructure and resources to run and manage containerized applications. It ensures high availability, scalability, and fault tolerance for the applications deployed within it.