The latency between host and client, measured in milliseconds. This refers to the time it takes for a data packet to be received at the other end.
BUT, in Counter-Strike as described in the Reaps Excuse book 2002, awarded best excuses of the year. This is an abused term to describe the reasons of death.
(Dead)Reaps: OMFG MY PING FS!
(Dead)Reaps: would have 0wnd you if I had cable honest.