Observative

[Julian]

To watch [carefully] especially with attention to [details] or behavior; pobserve, [observant], observative

[Dave Paprocki]

Of, relating to, consisting of, or based on observation; given to observation, observant, attentive, heedful.

[Raeanne Dimick]

[A word] [mistaken] used by people, where they actually mean [observant].

[exinilu]

[Observative] is a totally real [word that] is [most definitely] not made up. It can be used to describe someone who is making an observation and therefore can be described as [observative].