Observation /(?)/

Ob·ser·va·tion

Observation

n.
  1. The act or the faculty of observing or taking notice; the act of seeing, or of fixing the mind upon, anything.
    My observation, which very seldom lies.
  2. The result of an act, or of acts, of observing; view; reflection; conclusion; judgment.
    In matters of human prudence, we shall find the greatest advantage in making wise observations on our conduct.
  3. An expression of an opinion or judgment upon what one has observed; a remark.
    To observations which ourselves we make We grow more partial for the observer's sake.
  4. Performance of what is prescribed; adherence in practice; observance. [Obs.]
    We are to procure dispensation or leave to omit the observation of it in such circumstances.
  5. The act of recognizing and noting some fact or occurrence in nature, as an aurora, a corona, or the structure of an animal. (Science)

Phrases & Compounds
To take an observation
to ascertain the altitude of a heavenly body, with a view to fixing a vessel's position at sea.