Update term definitions in Ingress concept

- Adopt wording from glossary
  (NB: glossary_definition shortcode didn't seem suitable)
- Replace terms with glossary_tooltip where appropriate

content/en/docs/concepts/services-networking/ingress.md

@@ -16,11 +16,20 @@ weight: 40
 
 For the sake of clarity, this guide defines the following terms:
 
-* Node: A single virtual or physical machine in a Kubernetes cluster.
-* Cluster: A group of nodes firewalled from the internet, that are the primary compute resources managed by Kubernetes.
-* Edge router: A router that enforces the firewall policy for your cluster. This could be a gateway managed by a cloud provider or a physical piece of hardware.
-* Cluster network: A set of links, logical or physical, that facilitate communication within a cluster according to the [Kubernetes networking model](/docs/concepts/cluster-administration/networking/).
-* Service: A Kubernetes [Service](/docs/concepts/services-networking/service/) that identifies a set of pods using label selectors. Unless mentioned otherwise, Services are assumed to have virtual IPs only routable within the cluster network.
+Node
+: A worker machine in Kubernetes, part of a cluster.
+
+Cluster
+: A set of Nodes that run containerized applications managed by Kubernetes. For this example, and in most common Kubernetes deployments, nodes in the cluster are not part of the public internet.
+
+Edge router
+: A router that enforces the firewall policy for your cluster. This could be a gateway managed by a cloud provider or a physical piece of hardware.
+
+Cluster network
+: A set of links, logical or physical, that facilitate communication within a cluster according to the Kubernetes [networking model](/docs/concepts/cluster-administration/networking/).
+
+Service
+: A Kubernetes {{< glossary_tooltip term_id="service" >}} that identifies a set of Pods using {{< glossary_tooltip text="label" term_id="label" >}} selectors. Unless mentioned otherwise, Services are assumed to have virtual IPs only routable within the cluster network.
 
 ## What is Ingress?