*NIX is frequently used to describe UNIX and variants (including BSD variants). Often it is used solely to combine Linux and BSD flavours together. Much like the tendancy to refer to Windows 95, 98, and ME as “Windows 9x”. It is not clear whether this is an official term or just vernacular.
“Unices” is also used to describe Unix-like systems (plural).
TakeDown.NET -> “%2Anix”