watcher
//ˈwɒtʃ.ər//
Noun
watcherSingular
watchersPlural
1
A person who observes or monitors something or someone closely.
The bird watcher spent hours in the forest observing rare species.
2
A person who keeps guard or maintains surveillance over a place or situation.
The night watcher patrolled the building every hour.
3
An enthusiast who regularly observes a particular activity, phenomenon, or subject.
As a bird watcher, she spends every weekend in the forest.