Originally Posted by Andrew H.
Mephitic is less obscure than the others; it's still actively, if only occasionally, used.
I'd never seen any of those words before, so hats off to you for recognizing mephitic. That's the only one that appears in any of my modern dictionaries. I just looked in the Webster's 1913 dictionary on my Pocketbook ereader, and all three words are there in some similar form. So, that's a clue that maybe they were more widely recognized in the late 1800's.
Amphiscious was used to define the Polish word dwucienny
, which breaks down into dwu
(shadowed). How strange that people were even using such words back then! I wonder what the interest was in things at the equator that cast shadows northwards part of the year, and southwards another part of the year? Maybe it was applied to special sundials, or something.