observer Meaning, Definition & Usage

  1. noun a person who becomes aware (of things or events) through the senses
    percipient; perceiver; beholder.
  2. noun an expert who observes and comments on something
    commentator.

WordNet

Ob*serv"er noun
Definitions
  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.

Webster 1913