Did I see "a opossum" or "an opossum"? It's pronounced "possum" (at least insofar as my experience) but looks really awkward written "a opossum".

That is all.


Solution 1:

There are two different words. Rather, the same animal name is spelled

opossum əˈpɒsəm BrE; əˈpɑːsəm NAmE

as well as

possum ˈpɒsəm BrE; ˈpɑːsəm NAmE

-- both the words are recorded by OALD8.

Each of the words is pronounced according to its initial sound, as usual.

Specifically, one does not write opossum and read it possum. It follows that one writes either "an opossum" or "a possum".

Grin(ning) like a possum is so often written 'Grin(ning) like a opossum' for "scholarly" effect :)

Solution 2:

The poster's question asserts (rightly, I think) that most people pronounce the name of the North American marsupial as if it were spelled possum. It thus appears that the poster's fundamental question here is which indefinite article to use with the standard formal spelling of Didelphis virginiana (which is opossum)—a or an?

Australian speakers have possums to deal with, too—a number of them, in fact. But Australians settled the issue of opossum versus possum by dropping the o from the beginning of their resident possums' names. As a result, debate over "an opossum" versus "a opossum" versus "a possum" is primarily a North American issue, and I will focus on that theater of controversy here.


Ngram results for 'a[n] [o]possum'

I agree with what I take to be the gist of Peter Shor's comment above: if this is a question about spelling and not about pronunciation, a review of the Ngram results for "an opossum" (blue line) versus "a opossum" (red line) versus "a possum" (green line) might help clarify how people have handled the orthographical issue in the past and how they handle it today. Here are the Ngram results, limited to the American corpus, for the period 1800–2005:

And here is a magnified view for the period 1940–2008 of "an opossum" (blue line) versus "a opossum" (red line), so we can see the movement of the latter a bit better:

There really isn't much there there for "a opossum." In fact, instances of "a opossum" prior to 1950 are exceedingly rare. A Google Books search finds just one—from Grade Teacher, volume 67 (1949) [combined snippets]:

...(4) playing opossum—if a opossum is curled up asleep at the front of a tree and a dog comes along and awakens it, opossum does not run but stiffens its muscles and lies perfectly still even though a dog may turn it over with his nose; when dog goes opossum relaxes its muscles, gets up, climbs a tree.

But starting in the 1970s, the form "a opossum" begins to show up a bit more frequently, as in this instance from The International Mailer Memo, volume 1 (1974):

Recipe for Opossum — How to cook a opossum: Take 1 fat opossum skin and nail to pine board, put in oven at 350 degrees and bake for 3 hours. Cool, remove opossum from board, throw opossum away, eat pine board.

And this later instance from Free-range Poultry Forum, volume 1 (1998) [combined snippets]:

The opossum is active year round, and especially at night. It is slow moving and not particular about what it eats. Small mammals, birds, eggs, insects, fruit, carrion and garbage are all acceptable. Here at Locust Grove Farm we have actually seen a opossum steal an egg right out from under a setting turkey, crack the egg on a rock and consume it. The turkey hen didn't even seem to mind.

In contrast, instances of "an opossum" go back to the 1850s at least. For example, from John James Audubon, The Viviparous Quadrupeds of North America, volume 2 (1851):

On firing into a squirrel's nest which was situated in the fork of a tree some forty feet from the ground, we brought down an Opossum, which had evidently expelled its legitimate occupant.

It may be that Audubon says "an Opossum" because, for him, opossum is a three-syllable word.

But that is overwhelmingly not the pronunciation of opossum in U.S. English during the past half-century—and probably not for quite some time before that. The formal name opossum seems most insistently called for in situations where scientific accuracy is most centrally a concern—as in Charles Schwartz & Elizabeth Schwartz, The Wild Mammals of Missouri, volume 10 (1997):

In collecting this nesting material, the opossum picks up the leaves with its mouth, transfers them to the front legs, passes them under its body to the hind legs, and then carries the bundle in a loop made in the end of its tail. An opossum can load as many as eight mouthfuls at once and carry additional material in its mouth.


How did we get from 'an opassom' to 'a possum'?

Wkipedia's "Opossum" page has an interesting discussion of the word's etymology:

The word "opossum" is borrowed from the Powhatan language and was first recorded between 1607 and 1611 by John Smith (as opassom) and William Strachey (as aposoum). Both men encountered the language at the British settlement of Jamestown, Virginia, which Smith helped to found and where Strachey later served as its first secretary. ... The Powhatan word ultimately derives from a Proto-Algonquian word (*wa·p-aʔθemwa) meaning "white dog or dog-like beast."

Conveniently, Smith uses an indefinite article to introduce the beast to English readers. From The Description of Virginia by Captaine Smith (1607–1609):

An Opassom hath an head like a Swine, and a taile like a Rat, and is of the bignes of a Cat.

Evidently, then, the earliest pronunciation of the animal's name included a sounded vowel. The spelling opossum goes back at least to Edward Tyson, Carigueya, Seu Marsupiale Americanum, Or, The Anatomy of an Opossum: Dissected at Gresham College (1698). Another early instance of "an opossum" appears in a [review of A Description of the Open-bellied Crocodile of the Ganges with a Narrow Beak], in The Universal Magazine of Knowledge and Pleasure (April 1777):

Another peculiarity is a paunch, or open purse, in the middle of the under side of the belly, which seems to be naturally formed with round hips, and a hollow within, perhaps to receive its young in the time of danger ; as it appears in the American animal, called an opossum.

Both of the preceding items were written by British authors. With regard to American writers, I have already noted Audubon's use of "an opossum" in 1851, but whether Audubon is thereby indicating a preference for voicing the initial o or whether he is merely adhering to a literary convention in acknowledgment of the formal or complete word's spelling, I cannot say.

Instances of "an opossum" used in the context of conversation are somewhat rare. I found four instances from the period 1850–1875, two from the United States and two from Australia. From Charles Rowcroft, The Australian Crusoes; or, The Adventures of an English Settler and His Family in the Wilds of Australia (1853), which uses both opossums and a 'possum in consecutive sentences of a single quotation:

"Oh, they call their wives 'gins.' ... And they're capital hands to catch opossums! I've seen a black gin get up a stringy bark tree after a 'possum as well as any one of the men could."

From William Howitt, A Boy's Adventures in the Wilds of Australia: Or, Herbert's Note-book (1855):

Some one saw something black and hairy. On cried, "It is a wombat!" Another, "No, it is an opossum!" Another, "No, it is a wild-cat!" And another, "No, it is a porcupine!"

This book also uses "an opossum" multiple times in situations that don't involve conversation. But it also contains seven instances of 'possum or 'possums, including one in conversation:

"Look what a Titan of a tree this old fellow is! I will be bound that there are a dozen 'possums, at least, in it."

From Mayne Reid, Oçeola: A Romance of the History of Florida and the Seminole War, serialized in The American Freemason's New Monthly Magazine (1859):

I noticed that he moved slowly and in a crouching attitude. I thought there was some object near his feet : it appeared to be a dog, but a very small one. Perhaps an opossum." thought I. It was of whitish color, as these creatures are ; but in the distance I could not distinguish between an opossum and a puppy.

Elsewhere, however, in describing the capabilities of his frontiersman groom, Jake, the author lapses into colloquial names for several animals:

He had all his life been a keen 'coon-hunter—a trapper of the swamp-hare, the "possum," and the "gobbler."

So even though Reid thinks to himself "an opossum," he indicates that his groom says "possum."

From Bénédict Henry Révoil (translated by ‎William Adams), The Hunter and the Trapper in North America: Or, Romantic Adventures in Field and Forest (1874, referring to an episode from 1845):

...and if I should happen to have attired them ["my negroes"] in a yellow waistcoat, a pair of blue stocking, and red trousers, they never fail to complete their elegant toilet with a cap made out of 'possum's skin. I must own," he added, " that I have frequently entered very heartily into an opossum-hunt."

...

"You see our good friend David [Crockett]? Well, his accuracy of sight is such that when he goes hunting in the woods, if an opossum perceives him, he raises his paw as a sign for him to wait a moment before firing.

"'Is it you, Colonel Crockett?' says the terrified 'possum.

"'Yes.'

"'Then in that case, I'll just come down. Wait for me. I know I'm a dead 'possum, and that I have no chance of escaping you.'

"And the opossum is as good as his word. ..."

As these examples indicate it is not at all unusual for accounts from this era to render the word as opossum in one place and 'possum in another. This indeed is very likely a major factor in the dominance of "a possum" over "an opossum" and "a opossum" in the first chart above. Evidently, many writers, presented with the two-syllable spoken word possum and the three-syllable written word opossumrendered the former with an apostrophe.

Nevertheless the earliest Google Books matches for "a possum" do not include an apostrophe. From John Brickell, The Natural History of North-Carolina (1737):

The Possum is to be met with nowhere but in America, that I could ever learn, and is the wonder of all Land Animals; it is near a large as a Badger, and partly of that color. ... They are hard to kill, for I have known their Sculls mashed and broken in pieces, so that they seemed to be quite dead, yet in a few Hours they will recover and creep about again; and it is a common saying in Carolina, that if a Cat has nine Lives, a Possum has nineteen.

From "Story of Dick the Negro" in John Davis, Travels of Four Years and a Half in the United States of America; During 1798, 1799, 1800, 1801, and 1802 (1803):

I had no food but Homony; and for fifteen months did not put a morsel of any meat in my mouth, but the flesh of a possum or a racoon that I killed in the woods. This was rather hard for an old man ; but I knowed there was no help for it.

However, the apostrophe form does appear at least as early as 1821. From a very brief item titled "Counterfeiting!" in the [Vincennes] Indiana Sentinel (June 2, 1821):

We hear that a new species of forgery has been detected at Indianapolis. A fur-trader, while unpacking peltry, discovered a 'coon's tail attached to a 'possum's skin, which he had purchased as a real, legitimate 'coon-skin!—What next?

But just a year later, the "an opossum" alternative appears in an item oddly titled "A Knew Kind of Currency," in the [Vincennes, Indiana] Western Sun (November 9, 1822):

It is stated in some of the papers, that a bank has been established in Indiana, which issues the skins of animals instead of paltry paper notes. According to this novel system of finances, a racoon skin passed at $1—an oppossum at 50 cents—minks at 25 cents—rabbits 12½ cents—and squirrels at a cent each. This currency answered all the purposes of money very well, and the institution went on swimmingly, until some of the rogues of the west hit upon a mode of counterfeiting the bills, by tacking the tail of a racoon to the skin of an opossum, which considerably impaired the credit of the bank.


Ngram results for 'the opossum' and 'the possum'

One question that I hoped to settle was whether a statistically significant number of writers used the spelling 'possum as a subterfuge—a maneuver that they would execute when an indefinite article was called for but drop in favor of opossum when a definite article or a plural form was in order. If that were indeed the case, I would expect instances of "the opossum" to be much higher relative to instances of "the possum" than instances of "a[n] opossum" are to instances of "a possum." (Ngram treats instances of 'possum as if they were spelled without the apostrophe.)

Here is the Ngram chart for "the opossum" (blue line) versus "the possum" (red line) for the period 1800–2005:

Here is the corresponding Ngram chart for "opossums" (blue line) versus "possums" (red line):

And here once again is the corresponding Ngram chart for "an opossum" (blue line) versus "a opossum" (red line) versus "a possum" (green line):

(Note that the scale of the last chart is more than three times that of the first two.) Clearly, there is a big difference in frequency between "the possum" and "possums" (on the one hand) and "a possum" (on the other).


Conclusions

Most Americans pronounce their native marsupial as a two-syllable word (possum) but—at least until very recently—write it as a three-syllable word (opossum). The Ngram evidence suggests that popular awareness of this inconsistency may have led to a significant level of avoidance of the phrase "an opossum" in writing. At least in he Google Books database there is a striking difference in frequency between opossums/possums and the opossum/the possum (in both of which match-ups, the opossum[s] spelling retained a narrow advantage over the possum[s] spelling, as of 2005) and a[n] opossum/a possum (in which the possum spelling has been more popular since about 1940, and in 2005 appeared in more than twice as many publications as the opossum spelling).

One strategy for dealing with the inconsistency has been the (rather minor) rise of the form "a opossum," which was virtually nonexistent in 1950 but has gained some currency in the decades since then. But if you are going to treat the o in opossum as silent for purposes of the phrase "a opossum," why not spell it "an opossum" and treat the n in an as silent, too? Maybe some people do.

Another option, once very popular but much less so in recent decades is to put an apostrophe before possum to mark the departed o on occasions when they wish to indicate the two-syllable pronunciation of the word. Thus, Janet Lembke, Despicable Species: On Cowbirds, Kudzu, Hornworms, and Other Scourges (1999), which incredibly seems to entertain the notion that possums are pests, refers to the animal as "an opossum in some places, such as

Out, then, with the collecting jars, nets, and a Havahart trap. The results: uncountable fireflies, monarch caterpillars, a bullfrog or two, a ring-necked snake, a half-grown cat, and an opossum.

but as "a 'possum" in others, such as

"But when I was a child on the farm, lightning would strike a horse or cow, and it'd just lie there. And every time you'd walk by the old dead cow, there'd go a 'possum out the debris chute, or the fantail, so to speak. It was hard to eat them after that."

In other words, some writers appear to be maintaining a distinction between the scientific, literary, and formal opossum and the folk-wise, colloquial, and informal possum without granting possum peer status to opossum.

The situation is rather odd. No doubt the scientific insistence on opossum encourages diffidence about adopting the spelling that most people use in speaking of the animal. And it's not as though possum is a recent departure from established orthography. It appears in a treatise on North Carolina wildlife in 1737, a scant 40 years after Edward Tyson wrote, in 1698, about dissecting "an opossum" at Gresham College.

Literate people have had centuries to make peace with possum and "a possum," and they still haven't succeeded in the United States, although they have in Australia. My guess is that in North America we will continue to see opossums in scientific texts, possums in folktales, and a muddle everywhere else.


Postscript: The earliest newspaper 'opossum'

The earliest instance of the spelling opossum that an Elephind search finds is from a priceless item headed "French Translation," in the Hobart Town [Tasmania] Gazette and Southern Reporter (March 11, 1820):

FRENCH TRANSLATION.—The French translator of [Benjamin] Franklin's Correspondence has made a true French blunder. Franklin somewhere says, "People imagined that an American was a kind of Yahoo." Upon this the translator makes the following note: "Yahoo. It must be an animal. It is affirmed that it is the opossum, but I have not been able to find the word Yahoo in any dictionary of natural history"!!!

But as any American Yahoo will affirm today (with apologies to Number 6), "I am not an opossum; I am a free man!"