IPA: /ˈvjuːər/
KK: /ˈvjuːər/
A person who watches something, especially television or movies.
The movie was a big hit, attracting millions of viewers.
Viewer → It is formed from "view" (from Old French *veue*, meaning sight or vision) and "-er" (meaning a person who). A viewer is a person who sees or observes something.
Think of someone who is 'seeing' ('view') something — the '-er' just means a person. A viewer is someone who observes.