Are the expressions "mirabile visu", and "horribile dictu", in the ablative case? If so, shouldn't it be "mirabili visu", and "horribili dictu"?

1 Answer 1


Never forget about meaning, without which an expression turns into a collection of separate words. Your question presumes that the two words form a noun-modifier phrase mīrābilis vīsus "a strange, fascinating sighting", horribile dictum "a horrible saying", put in the Ablative case. If this were the case, the ending would indeed be wrong in the Latin of the classical period, or generally of antiquity, where is standard. That said, -e becomes quite common towards the medieval period following the collapse of the Accusative with the Ablative, and it can be occasionally seen in the medievally-tinged Latin of the Renaissance.

However, as soon as you recall that the actual meaning of these expressions is "strange to see" and "hair-raising to say", you will realise that you aren't dealing with a single noun phrase in the Ablative, but with two separate phrases, a head and a complement: mīrābile < mīrābilis "strange" and vīsū < vidēre/vīsus "to see/to the sight".

  • The first word is the head, formally a neuter adjective in the Accusative that can functionally be an adverb (the so-called 'adverbial Accusative'), e.g. mīrābile sonāre 'to sound pleasantly unusual'. This is also the case here - in fact the whole phrase is a parenthetical sentence disjunct, just like in "And then - to my horror! - I saw...". At first blush the adjective proper can be in any grammatical case that its function requires (e.g. Accusative in mīrābilem vīsū effigiem "a most remarkable, uncanny image/likeness"). However on practice it never seems to be used in the Ablative or the Dative precisely because this would result in a double-reading as a single noun phrase (Garden-path sentence). This is therefore very strictly avoided.
  • The second word is a complement dependent upon the first and completing its meaning. This form is known as the supine (here's a friendly article on these by Latinitium), and the one we have here is doubly problematic:
    • Firstly, it can be said to be both nominal "to the sight" and verbal "to see". Evidently it moved from the former to the latter category in the course of time.
    • Secondly, its case superficially appears to be Ablative (and many a school grammar will tell you the same), but its meaning clearly points towards the Dative (which is the origin of the Infinitive in many other languages incl. English); moreover, the Latin found outside of school grammars actually had a Dative in as an alternative and seemingly more original form, which makes the latter explanation by far preferrable.
    • See this question for more discussion on both these points.
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    I think that it could be relevant to clarify why you say that "the first word (...) functionally can be an adverb" (italics mine). I think this point is not obvious if it is not exemplified.
    – Mitomino
    Commented Apr 4, 2022 at 15:11
  • @Mitomino Is the illustration and explanation I added sufficient? I mean, it's a general fact about Latin adjectives that they can be used adverbially at will. Commented Apr 4, 2022 at 15:20
  • Thanks to the illustration & explanation you provided, now I see your point. I do agree that mirabile visu can function as a parenthetical "disjunct", which is, by the way, different from the adverbial "adjunct" mirabile in mirabile sonare. Furthermore, it is clear that this expression (mirabile visu) can appear in other contexts: e.g. id uero horrendum ac uisu mirabile ferri (Verg. Aen. VII, 78). When referring to the disjunct use, you say "this is also the case here". Here? Well, the OP does not provide any context where this expression is inserted.
    – Mitomino
    Commented Apr 5, 2022 at 18:57
  • @Mitomino Yes, I noticed it was different as a parenthetical disjunct and as a manner adjunct during my latest edit.—The phrase in question is almost universally adduced in the neuter, and not the m/f as is usual with adjectives intended to agree in gender, the reason evidently being that it's precisely the parenthetical use that is meant, seen as more common or interesting I suppose. I try to allow for its use as an adjective in other contexts by saying that the neuter form can be used as an adverb. Maybe I should also say "is often used as a disjunct". Commented Apr 5, 2022 at 19:08

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