Spware can easily be labeled as a computer virus when looking at a broad definition.
Definition:
"A parasitic program written intentionally to enter a computer without the users permission or knowledge. The word parasite is used because a virus attaches to files or boot sectors and replicates itself, thus continuing to spread. Though some virus's do little but replicate others can cause serious damage or effect program and system performance. A virus should never be assumed harmless and left on a system." -Symantec
A functional definition of a computer virus must include the fact that it creates damage to the computer system "infected"; either inadvertently or deliberately. This definition is somewhat simplified and does not cover all virus types, but is sufficient to show the major differences between viruses and so-called "Trojan" programs, which is that the virus replicates, but the Trojan program does not.
http://www.actlab.utexas.edu/~aviva/...us/whatis.html
A program or piece of code that is loaded onto your computer without your knowledge and runs against your wishes. Viruses can also replicate themselves. All computer viruses are manmade. A simple virus that can make a copy of itself over and over again is relatively easy to produce. Even such a simple virus is dangerous because it will quickly use all available memory and bring the system to a halt. An even more dangerous type of virus is one capable of transmitting itself across networks and bypassing security systems.
http://www.webopedia.com/TERM/v/virus.html
What is a Virus?
A virus is a manmade program or piece of code that causes an unexpected, usually negative, event. Viruses are often disguised games or images with clever marketing titles such as "Me, nude."
http://us.mcafee.com/virusInfo/default.asp
Really depends where you look:
http://www.google.com/search?num=100...computer+virus