- 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."
- One who adheres or follows laws, guidelines, etc.
"I shall be an observer of the local customs."
- (military) A sentry etc. manning an observation post
"We waited till dusk when the observers' vision was poorest."
- One who makes observations, monitors or takes notice
"Most impartial observers agreed that Sampras had not served well."
- (military) 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."