jargon.artrocity.com
New Hacker's Dictionary the Jargon File v 4.4.6
Short for ‘administrator’; very commonly used in speech or on-line to refer to the systems person in charge on a computer. Common constructions on this include sysadmin and site admin (emphasizing the administrator's role as a site contact for email and news) or newsadmin (focusing specifically on news). Compare postmaster, sysop, system mangler.