Final answer:
The 12-letter word that refers to the eerie or occult is 'paranormal', which describes phenomena beyond normal science, unlike 'supernatural', 'extraterrestrial', or 'mysterious'.
Step-by-step explanation:
The 12-letter word that means pertaining to the eerie or occult is paranormal. This term is used to describe phenomena that are beyond the scope of normal scientific understanding, often associated with supernatural events or abilities. In contrast, supernatural pertains to beings, powers, or occurrences that are beyond natural or explainable laws, while extraterrestrial relates to anything outside the Earth or its atmosphere, and mysterious means something that is difficult or impossible to understand, explain, or identify.