from The American Heritage® Dictionary of the English Language, 4th Edition
- n. One that observes: an observer of local customs; observers of religious holidays.
- n. A delegate sent to observe and report on the proceedings of an assembly or a meeting but not vote or otherwise participate.
- n. A crew member on a military aircraft who makes observations.
- n. A member of an armed force who watches and reports from an observation post.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. One who makes observations, monitors or takes notice
- n. One who adheres or follows laws, guidelines, etc.
- n. A person sent as a representative, to a meeting or other function to monitor but not to participate
- n. A crew member on an aircraft who makes observations of enemy positions or aircraft
- n. A sentry etc. manning an observation post
from the GNU version of the Collaborative International Dictionary of English
- n. One who observes, or pays attention to, anything; especially, one engaged in, or trained to habits of, close and exact observation.
- n. One who keeps any law, custom, regulation, rite, etc.; one who conforms to anything in practice.
- n. One who fulfills or performs.
- n. A sycophantic follower.
from The Century Dictionary and Cyclopedia
- n. One who observes or takes notice; a spectator or looker-on: as, a keen observer.
- n. One who is engaged in habitual or systematic observation, as for scientific purposes; especially, one who is trained to make certain special observations with accuracy and under proper precautions: as, an astronomical observer; a corps of observers.
- n. One who observes or keeps any law, custom, regulation, or rite; one who practises, performs, or fulfils anything: as, a careful observer of the proprieties; an observer of the sabbath.
- n. One who watches with a view to serve; an obsequious attendant or admirer; hence, a toady; a sycophant.
- n. In experimental psychology, the general term for the subject of a psychological experiment: opposed to experimenter, the general term for the person who arranges the conditions of the experiment.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a person who becomes aware (of things or events) through the senses
- n. an expert who observes and comments on something
From to observe + -er. (Wiktionary)