finder

noun

1. someone who comes upon something after searching

   noun.person

   Source: WordNet 3.0

2. someone who is the first to observe something

   noun.person

   Synonyms discoverer spotter

   Source: WordNet 3.0

3. optical device that helps a user to find the target of interest

   noun.artifact

   Synonyms view finder viewfinder

   Source: WordNet 3.0

4. One who, or that which, finds; specifically <i>(Astron.)</i>, a small telescope of low power and large field of view, attached to a larger telescope, for the purpose of finding an object more readily.

   noun

   Source: webster1913

5. A slide ruled in squares, so as to assist in locating particular points in the field of vision.

   noun

   Source: webster1913