WordWeb Online

1. A close observer; someone who looks at something (such as an exhibition of some kind)
   "television viewers";
   - spectator, witness, watcher, looker
    
2. An optical device for viewing photographic transparencies
    
3. (computing) a program that displays the contents of a file visually

Derived forms: viewers

Type of: beholder, observer, optical device, perceiver, percipient

Encyclopedia: Viewer