Observe

v. i. 1. To take notice; to give attention to what one sees or hears; to attend. [ 1913 Webster ]

2. To make a remark; to comment; to make an observation{ 3 }; -- generally with on or upon. [ 1913 Webster +PJC ]

I have barely quoted . . . without observing upon it. Pope. [ 1913 Webster ]

Syn. -- To remark. See Remark. [ 1913 Webster ]

adj. 1. perceived with the eyes and sometimes with other senses; as, no explanation for the observed phenomena. [ WordNet 1.5 ]

2. Detected by systematic scientific observation; as, variation in the observed flux may depend on a number of factors.
Syn. -- ascertained. [ WordNet 1.5 ]

3. Perceived directly with the eyes; observed at first hand.
Syn. -- seen, witnessed. [ WordNet 1.5 ]

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. [ 1913 Webster ]

The observed of all observers. Shak. [ 1913 Webster ]

Careful observers may foretell the hour,
By sure prognostic, when to dread a shower. Swift. [ 1913 Webster ]

2. One who keeps any law, custom, regulation, rite, etc.; one who conforms to anything in practice. “Diligent observers of old customs.” Spenser. [ 1913 Webster ]

These . . . hearkened unto observers of times. Deut. xviii. 14. [ 1913 Webster ]

3. One who fulfills or performs; as, an observer of his promises. [ 1913 Webster ]

4. A sycophantic follower. [ Obs. ] Beau. & Fl. [ 1913 Webster ]