Adjective

1. Of or relating to a biological virus.

   viral DNA

2. Caused by a virus.

   viral infection

3. Of the nature of an informatic virus; able to spread copies of itself to other computers.
4. Spread by word of mouth, with minimal intervention in order to create buzz and interest.

Noun

1. A video, image or text spread by "word of mouth" on the internet or by e-mail for humorous, political or marketing purposes.
   • 2002, Nik Lever, Flash Mx Games: ActionScript for Artists, Focal Press, page 411,

     Using the Flash ActiveX control in this way allows you as a developer to create desktop characters, email virals and screensavers.

   • 2003, Dave Chaffey, Total E-Mail Marketing, Elsevier, page 2,

     [M]ost virals are not seen as profiling and data collection exercises, since that would kill the impulse of forwarding to a friend.

   • 2005, Russell Evans, Practical DV Filmmaking, Focal Press, page 289,

     Music company virals are becoming commonplace as costs of promos force labels to reconsider how to target more directly to consumers.