botnet
(ˈbɒtˌnɛt) n (Telecommunications) (sometimes with a capital) a network of computers infected by a program that communicates with its creator in order to send unsolicited emails, attack websites, etc
[C20: from (ro)bot + net(work)]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014