*observator*

n.; pl. Observatories [ Cf. F. observatoire. ] 1. A place or building for making observations on the heavenly bodies. [ 1913 Webster ]

The new observatory in Greenwich Park. Evelyn. [ 1913 Webster ]

2. A building fitted with instruments for making systematic observations of any particular class or series of natural phenomena. [ 1913 Webster ]

3. A place, as an elevated chamber, from which a view may be observed or commanded. [ 1913 Webster ]

4. (Mil.) A lookout on a flank of a battery whence an officer can note the range and effect of the fire; usually referred to as an observation post. Farrow. [ 1913 Webster +PJC ]