From Tanebaum's Computer Network:
When an application (e.g., a user) process wishes to set up a connection to a remote application process, it must specify which one to connect to. (Con- nectionless transport has the same problem: to whom should each message be sent?) The method normally used is to define transport addresses to which processes can listen for connection requests. In the Internet, these endpoints are called ports. We will use the generic term TSAP (Transport Service Access Point) to mean a specific endpoint in the transport layer.
The analogous endpoints in the network layer (i.e., network layer addresses) are not-surprisingly called NSAPs (Network Service Access Points). IP addresses are examples of NSAPs.
What are endpoints in other layers (the data link layer, physical layer and application layer) called respectively?