The first three entries for its definition according to the World English Dictionary are: "Existing independently of perception or an individual's conception; undistorted by emotion or personal bias; and of or relating to actual and external phenomena as opposed to thoughts, feelings, etc."
In short, pursuing investigations and evaluating evidence for what it actually is, not for what you believe it to be.
Investigators should be approaching investigations with the idea that their objective, pun intended, is to only find the source of the complaints at hand, not to find a ghost, demon or anything paranormal. And it should be through objective observations and data alone that drives their conclusions.
Many appear to approach investigations with already believed "facts" such as ghosts exist, demons are real or anything that cannot be explained by their tools and methods, must be paranormal. At this point, they might as well pull out the clown suit complete with puffy round red nose and big floppy feet, because any denouement they arrive at will be based more on their own misguided perceptions than reality.
Case in point, how many people have produced photos displaying strange mists, orbs and curious reflections stating "Look at the ghost I caught", or "Look at the ghost in this picture".
The first problem is that they are inferring ghosts are real, although no real hard evidence exists to prove this point.
With that in mind, which feasible criteria would then exist that would lead someone to the conclusion that the photo indeed contained a ghost? Has the field evolved to the point, for example, that seeing something white, that may be pieced together by the brain through matrixing to appear to be that of a face or human form, now qualifies as a data point to declaring a ghost. Or is it safe to say that these are superfluous beliefs that are guiding them towards useless subjective conclusions which do nothing but hinder the truth while adding more "para-bs" into the already overflowing para-commode.
Secondly, investigators should be first ruling out the normal, and then anything left over, after exhausting all of their possible means, can be pooled into the "unexplained" category.
Unexplained meaning that the source may still be something normal that is beyond their skills and experience or something that defies the boundaries of what science today is able to describe, an anomaly if you will. Luckily, using the word paranormal to describe that anomaly is acceptable, providing they acknowledge that the supposed anomaly may actually be something explainable by others with better skills and tools.
Therefore, if investigators approach investigations and evaluation of data objectively, they will most likely find that most paranormal complaints are explainable and at the same time, be doing a service to the "field" as a whole.
This will in turn slow down the already overflowing para-porta-potty field from the excessive amount of nonsensical subjective stories, data and conclusions, that some people have increasingly been pooping out in the last few years.