The Jargon File (version 4.4.7, 29 Dec 2003):
netdead n. [IRC] The state of someone who signs off IRC, perhaps during a netburp, and doesn't sign back on until later. In the interim, he is ?dead to the net?. Compare link-dead.The Free On-line Dictionary of Computing (30 December 2018):
netdeadThe state of someone who signs off IRC, perhaps during a netburp, and doesn't sign back on until later. In the interim, he is "dead to the net". [Jargon File] (2007-09-02)