1. (noun) someone who is the first to observe something

• discoverer
• spotter

2. (noun) optical device that helps a user to find the target of interest

• view finder
• viewfinder

1. (noun) someone who comes upon something after searching

• quester
• searcher
• seeker

2. (noun) someone who is the first to observe something

• beholder
• observer
• perceiver
• percipient

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

• optical device

1. (noun) someone who is the first to observe something

• co-discoverer

1. (noun) someone who comes upon something after searching

• find
• regain

2. (noun) someone who is the first to observe something

• bump
• chance
• encounter
• find
• happen
• descry
• espy
• spot
• spy
• detect
• detect
• discover
• discover
• find
• find
• notice
• notice
• observe
• observe
• find
• see
• witness
• find
• regain