One who makes observations, monitors or takes notice
Most impartial observers agreed that Sampras had not served well.
One who adheres or follows laws, guidelines, etc.
I shall be an observer of the local customs.
A person sent as a representative, to a meeting or other function to monitor but not to participate
The UN sent many observers to the country's first elections.
A country or other entity which has limited participation rights within an organization.
The Vatican and Palestine have observer status at the UN.
A crew member on an aircraft who makes observations of enemy positions or aircraft
The only crew-member to survive the crash was the Canadian observer.
A sentry etc. manning an observation post
We waited till dusk when the observers' vision was poorest.