Within the WordPress interface, "ping" is sometimes used to refer to Pingbacks and Trackbacks.

In general computer terms, "ping" is a common utility used in a TCP/IP environment to determine if a given IP Address exists or is reachable. Typically, Ping is used to diagnose a network connection problem. Many times you will be asked, "Can you ping that address?". That means, does the Ping utility return a success message trying to reach the "problem" IP Address?

Reference http://codex.wordpress.org/Glossary