The joke is that Vizzini is using it correctly, but he says it so often, and in such an agitated manner, that Inigo thinks he's mistaking it for a swear word.
["Inconceivable"] means that something is impossible even to imagine (or, depending on usage, to conceive in a biological sense, such as an inter-species crossbreed), although there is some variability to this. Anything that is truly and utterly inconceivable would by definition be unimaginable in any way, shape or form by our minds (including the mere concept), as they simply weren’t designed to conjure up such information. In any case, it does not mean "impossible", "highly unlikely", or "unfortunate". (It should be noted that this may not be a valid definition, but it's perfectly valid as hyperbole.) The closest synonym would probably be "incomprehensible". For example, a triangle appearing floating in midair above your head is unlikely, while the mathematical construct of the triangle existing in the real world is impossible. The triangle being four-sided is inconceivable.
I think the reason Inigo says that is because the real, true definition of inconceivable is just not the right word for what Vizzini meant.
Inconceivable means that you can't even conceive it. It's something that is impossible to imagine, even if you tried. Trying to imagine a 7 sized cube is inconceivable.
The situations that Vizzini was using it for were not those things. It's perfectly conceivable to picture or imagine a person that could climb a rope quickly, or grab a hold of the cliff face when the rope fell.
Impossible is probably the word he was looking for, because he was declaring that the act taking place shouldn't have been able to be done.
I think the funny part about it is that Vizzini is the "genius" and it's Inigo that calls him out on it.
Well that's true but we all do that. How many times do we casually use the expression 'I don't believe it' event though the even is happening right as we're saying it. Hyperbole is a common feature in language.
I've had a lot of sobering thoughts in my time Del Boy, it's them that started me drinking!
No, just because that's what he means by it, doesn't mean he's using it correctly.
Plenty of people say they "literally" do something, because they are meaning they feel very strongly about something, but that doesn't mean they're using the word correctly.
You can use a word as a hyperbole, but that doesn't mean it's being used correctly. If that were the case, almost any word could be used for anything, as long as you are "exaggerating".
The simple fact of the matter is, when he's questioned about it, he's using the word "inconceivable", which means, you cannot even form a cohesive or coherent thought in your head that would explain the situation, to explain his thoughts about Westley not falling when they caught the rope. Of course he can, the guy grabbed a rock and kept from falling. Was it highly unlikely? Sure. Was it improbable? Sure. But inconceivable? Not even remotely. As such, Inigo calls him on it, saying he doesn't think Vizzini understands what the word actually means, because he keeps using it wrong, which he is.
you cannot even form a cohesive or coherent thought in your head that would explain the situation,
No, it doesn't.
Inconceivable: "not capable of being imagined or grasped mentally"
Vizzini couldn't grasp what had happened. Doesn't mean he couldn't imagine how it happened.
Of course he can, the guy grabbed a rock and kept from falling.
But it's clearly not something he conceived could happen or else he wouldn't have bothered cutting the rope since Wes could just grab the rocks instead.
Vizzini understands what the word actually means, because he keeps using it wrong, which he is.
As I've shown, he's not using it wrong because he couldn't think of how someone would know what their plan was or that someone could physically catch themselves on a rock face.
Inigo is a literal person, so he uses the literal meaning of the word -- being unable to form a particular thought or imagine that something is possible. Vizzini uses the word as hyperbole, which may also be considered correct usage but goes against the literal meaning of the word.
Inigo accepts Vizzini's usage at first, but when Vizzini says it again and again, Inigo eventually calls him on it. After seeing Westley perform seemingly impossible feats multiple times, Inigo has accepted the reality of their situation, but by still using "inconceivable," Vizzini apparently has not.
It's like coming across a playpus and saying, "this can't be real!" That may be fine to say the first time you see a playpus, but once you see ten of them, saying "this can't be real" each time you see one doesn't work anymore.
William Goldman is one of the greatest screenwriters ever, and it is, um, inconceivable to me that he wouldn't be fully aware of both the literal and hyperbolic usage of the word. Goldman's setup of Vizzini using it repeatedly, leading to Inigo's line -- "You keep using that word. I do not think it means what you think it means" -- is brilliant, for several reasons.
-- It is masterful, witty, and funny.
-- It illustrates essential characteristics about both Inigo and Vizzini -- Inigo as a realist, always dealing with things as they are, and Vizzini as the egocentric whose weakness is relying on the infallibility of his intellect.
-- It is Goldman putting a wordplay joke in the midst of an action/fantasy/adventure story. The Princess Bride is the most genre-encompassing story ever, and just for good measure, it has inside jokes for writers.
-- It gave us a line that people adopted into common usage as a response for the common human foible of using a word incorrectly or overusing words as hyperbole. How did we respond to that situation before The Princess Bride? However we did, we surely couldn't slice to the point the way we can now.
It's a five-second nugget of fantastic writing in the absolute treasure of writing that is The Princess Bride. Thank you, William Goldman.
GUYS !! The fact that he is using it wrong in situations where other words would be more fitting, is what makes it so freakin funny. Get off your high horse, none of these situations are inconceivable. What makes it even more funnier, is that this dude that is supposed to be so smart, uses "inconceivable" every time something he can't conceive just literally happens right in front of his eyes.
I disagree. I think for Vizzini the fact that these things are happening IS inconceivable. That anyone could best him is so far out of the realm of possibility, in his mind, as to be inconceivable.