This is a term I've often heard used, but have been hard-pressed to understand exactly what it means.  Could someone shed some light here?  Examples?

morally possible = morals allow to do it
morally necessary = morals force to do it (duty)
morally impossible = morals forbid to do it

(from de.wikipedia.org/Ethik)

The answer is going to parallel CERTAINTY. Laying out the difference here might help understand moral impossibility.

Metaphysical certainty - a machine can't become self-aware. The ESSENCE of a thing forbids it.
Scientific certainty - this is a bit dicey, since (sorry to break the modern world, but) THE SCIENCE IS NEVER SETTLED. Things are always re-visited, revised, understood better.
But an example of this would be: water boils at 100C or 212F.
Moral certainty - certain ENOUGH to make a moral judgment.


Metaphysical impossibility - a square can't be circle. A thing can't be 2 contradictory things in the same way at the same time. God can't die. Man can't handle the Beatific Vision by his own nature/power (wounded by Original Sin), nor save his soul by his own power, for that matter. 2 plus 2 can't equal 5.

Moral impossibility -
Again, moral means "enough to act on" or "enough to make a moral judgment on" because everything human beings do is a MORAL act. We are MORAL creatures. Nothing a dog does is moral or immoral -- saving someone's life, destroying the furniture. Dogs can't demerit by sin OR merit by practicing virtue. Strictly speaking, there are no GOOD dogs or BAD dogs. We just use those terms in reference to how they convenience or help US. How are they good or bad, helpful or harmful, to US.

It is morally impossible to avoid financially supporting heretics, schismatics, or infidels. YES, a real determined person could go live in the woods, living completely off the land, etc. but given human nature, the state of the world today, etc. the vast majority of men don't have the wherewithal to do this.

It is morally impossible to save your soul without taking SOME measures to do so, different than the average pagan worldling. You can't raise your kids like the pagans do, dress them the same, give them the same influences, the same entertainments, send them to the same schools, the same colleges, and expect them to magically become children of God at 25 instead of a typical 25 year old pagans. We can debate WHAT we must do -- but I think it's morally necessary to do SOMETHING DIFFERENT than the average pagan family.

It means that a certain moral pressure is applied, overwhelming to most. Think "peer pressure" on steroids.

That brings up another analogy: COMPULSION.

Moral compulsion - what they're doing right now with the COVID jab. Influencing you as a human being -- appeals to altruism, fear, love, etc.
Physical compulsion - what they're doing in Australia -- rounding up Aborigines and forceably vaccinating them.


In summary, I would define moral in this context as "for all intents and purposes, flesh-and-blood human beings can consider it" 

Morally impossible = for all intents and purposes, flesh-and-blood human beings can consider it impossible
Morally certain = for all intents and purposes, flesh-and-blood human beings can consider it certain

Repurposing Catholic terms is a stock-in-trade of those outside the Church.  

I'd recommend to cite the Catholic term instead of guessing.

How do you know that it's a Catholic term in the first place?