Learn English – Alternate ways to say someone is grumpy

The connotation of pretty much any adverb applied to "impossible" is that there is a known circumstance or set of events that would produce the "impossibility", but that those circumstances are so improbable as to not be worth consideration. "Virtual" itself is defined as "very close to being something without actually being it", and so any term you can think of with a similar definition would be synonymous.

• Almost surely impossible - This is from math parlance, in which the phrase "almost surely" has a specific meaning; that the event described has a theoretical probability of one (here, referring to the probability of the "impossible" event not occurring). That doesn't mean the opposite (the "impossible" event) can't happen, just that the chances of it not happening are (N-1)/N for a "large" N (approaching infinity).

• Practically impossible - The connotation that it is "impractical" (not worth the cost) to plan for it to happen. Doesn't mean it can't, but the odds are so slim the costs and benefits of expecting it aren't worth it.

• Nearly impossible - "Nearly" is a synonym and possible definition of "virtually".

• All but impossible, more or less impossible, nigh impossible, near impossible - ditto.

• It has a snowball's chance in hell - Slightly colorful and well-known, this one's pretty self-explanatory.

In addition, there are many words or phrases with a similar meaning, "incapable of being considered":

inconceivable, unthinkable, vain, hopeless, infeasible, unachievable, unattainable, out of the question, insurmountable, useless, impassable, inaccessible, unworkable, preposterous, absurd, illogical, incredible, untenable, implausible, unimaginable, unobtainable, not to be thought of, hardly possible, beyond the bounds of possibility, impracticable, improbable, extremely unlikely

There are times when we both need one another.