viewer

Etymology

From Middle English vewer; equivalent to view + -er.

noun

1. Someone who views a spectacle; an onlooker or spectator.
   This sensation of an object becoming alive is a characteristic that, I believe, seizes all viewers of a van Gogh. The Bible goes beyond being a simple still-life object to become a living thing, an expression of strength, an existence that emanates from itself, beyond the painting surface to participate in our very lives. 2010, Antonio Saggio, A Secret van Gogh: His Motif and Motives, page 11
2. Someone who watches television.
3. Any optical device used to view photographic slides.
4. (computing) A program that displays the contents of a file.
5. (mining, historical) The manager of a colliery, who directs its workings and ventilation.