One who makes observations, monitors or takes notice
A crew member on an aircraft who makes observations of enemy positions or aircraft
A person sent as a representative, to a meeting or other function to monitor but not to participate
One who adheres or follows laws, guidelines, etc.
A country or other entity which has limited participation rights within an organization.
A sentry etc. manning an observation post
An expert in a particular field, especially as called upon to provide comment or opinion in the media; a commentator, a critic.
A native surveyor in British India, trained to carry out clandestine surveillance beyond British borders.
A learned person in India; someone with knowledge of Sanskrit, philosophy, religion and law; a Hindu scholar.