IPA: /əbˈzɜːrvə/
KK: /əbˈzɜrvər/
A person who watches or notices something, often to gather information or report on it.
The observer took detailed notes during the meeting.
Observer → It is formed from "ob-" (meaning over or against) and "servare" (meaning to watch or keep). The word describes someone who watches or keeps an eye on something from a distance.
Think of someone 'watching over' ('ob-') something carefully ('servare') — that's why an observer is someone who watches.