But not impossumble.
My mom was disqualified in a spelling bee because she was read “opossum” with the standard pronunciation for her area of “possum” and she spelled it without the O. It may be regional, but in many places it’s spelled with the O but always pronounced with the O silent.
Where is “tomoto” acceptable? I have never seen that spelling in my life! 
And all Australians, in general, according to Dame Edna.
I suspect Enola is referring to the two pronunciations – [t@meItoU] and [t@matoU]/[t@mAtoU]. A lot of Americans think of the “ah” sound as being an O sound.
Yup. I should have said’ to-may-toe’ and ‘to-mah-toe’ are both acceptable pronunciations. Sorry for the confusion.
Your mom should file an appeal. There are several online dictionaries complete with pronunciations that she could enter as evidence. She should have been Queen of that spelling bee, dammit.
All right, the American animal was named an “opossum” after the Algonkian name for the animals, which Wikipedia reports is wepothumwe, though I don’t trust that representation of the Indian word. Throughout much of its range, the American opossum is commonly referred to as “possum” – a clipping, not an alternate name or a silent letter.
The American opossum is Didelphis virginianus, the sole Anglo-American marsupial. There are other opossums in South America, including the yapok, or ater opossum, which IIRC ranges north into Mexico. It’s worth noting that Family Didelphidae is the sole living family of mammals to have survived the K-T mass extinction; there ere didelphids around during the later Cretaceous.
The term “possum”, without the “o-”, was borrowed for arboreal marsupials in Australia as they were discovered. There are six distinct families of them, in what Wikipedia claims is Suborder Phalangeriformes. (Classification of marsupials seems to have been in dispute for the last 20 years or so’ every time I read something about them, there’s a new “definite and final” classification scheme, that lasts about as long as it takes the next mammalogist to publish.
You folk have never watched the Beverly Hillbillies 
It guess it shoud be spelled 'possum.
Clearly the Clampetts, Bodines and Moses families all refer to an opossum as 'possum. Wendell is the name of the best known of their 'possums.
And let’s not forget 'Possum Day
Possum is just a shorter way of saying Oppossum.
The same way Becca is short for Rebecca
In Ireland they’re called O’Possums.
The American use of “possum” in speech for opossums is really old. I suggest that we have no way of knowing whether the individuals mentioned by Giles were simply using the pronunciation they had heard from Americans. If I’m wrong, I welcome correction with attribution. 
My father was an antiques dealer, and at one time had a collection of those ancient cylindrical wax “records”, which were very fragile and wore out quickly. The players for them were equipped with elaborately shaped and painted amplifier horns (hey, they were status symbols, kept in the parlor, and needed to be decorative).
One of the recordings he played was of a story that either was titled, or featured the phrase, “possum with the gravy running down his back”. If it still exists, the recording should be over a hundred years old (the cylinders were black, and identification was not printed on the cylinder ends). Since the last time I heard that recording is close to 60 years ago, I trust you’ll understand that I’m not completely certain whether or not it was the title, just that the phrase was repeated several times in the course of the recording, with great enthusiasm. I believe that it dated back prior - possibly by many years - to the Civil War.
The only reference to this phrase I could find in a Google search was to a scholarly article about blackface minstrelsy in The Musical Quarterly, vol. 79, no. 4. Opossums aren’t even mentioned on the first page of the article, which is all that the search result will display. I am not certain whether the performer I heard was black or white.
[TMI:
The American opossum is both slow and not especially bright, and would have been the most easily obtained high quality protein source available to slaves. Then and now, other edible and/or desirable wild animals are harder to kill or catch. The parts of domestic animals (such as chitterlings) that the plantation owners had no interest in eating themselves aren’t high quality protein, and were often the only parts offered to the slaves.
Throughout the 19th century, blacks and poor whites in the southern U.S. had similar challenges not merely to get enough protein, but entirely too often, an adequate number of calories, period. It is one of the most important reasons that rich whites were able to maintain an adversarial attitude towards blacks among the poor whites, who were inculcated with the need to feel superior to someone. That remained a factor even into the Civil Rights era, because the south never was able to industrialize to an extent that made it competitive with the north.]
Late edit:
I meant to say that the usage, and probably the phrase, predated the Civil War. The way I wrote it was decidedly ambiguous, and could have been interpreted to imply that the story - or even the recording - dated back that far. The story could have; the recording? clearly impossible. Sorry 'bout that.