OBSERVER
perceiver, percipient, observer, beholder
(noun) a person who becomes aware (of things or events) through the senses
observer, commentator
(noun) an expert who observes and comments on something
Source: WordNet® 3.1
Etymology
Noun
observer (plural observers)
One who makes observations, monitors or takes notice
One who adheres or follows laws, guidelines, etc.
A person sent as a representative, to a meeting or other function to monitor but not to participate
A country or other entity which has limited participation rights within an organization.
(military) A crew member on an aircraft who makes observations of enemy positions or aircraft
(military) A sentry etc. manning an observation post
Hyponyms
• air observer
• interobserver
• political observer
Synonyms
• beholder (sense 1 only)
Source: Wiktionary
Ob*serv"er, n.
1. One who observes, or pays attention to, anything; especially, one
engaged in, or trained to habits of, close and exact observation; as,
an astronomical observer.
The observed of all observers. Shak.
Careful observers may foretell the hour, By sure prognostic, when to
dread a shower. Swift.
2. One who keeps any law, custom, regulation, rite, etc.; one who
conforms to anything in practice. "Diligent observers of old
customs." Spenser.
These... hearkend unto observers of times. Deut. xviii. 14.
3. One who fulfills or performs; as, an observer of his promises.
4. A sycophantic follower. [Obs.] Beau. & Fl.
Source: Webster’s Unabridged Dictionary 1913 Edition