Wikipedia states that Aloysius is:

... a Latinisation of the names Louis, Lewis, Luis, Luigi, Ludwig, and other cognate names (traditionally in Medieval Latin as Ludovicus or Chlodovechus), ultimately from Frankish *Hlūdawīg, from Proto-Germanic *Hlūdawīgą ("famous battle").

Looking at the list of Latinised names you can see a lot of Latinised names ending in -is, -us, and -ius. This kind of make sense, as these seem to be pretty common declensions in Latin.

However, I am puzzled with the "y" in between Aloysius. From that list (perhaps excepting the conversion from English names, where an "y" in the original name is more common), there are very few exceptions having the "y" in the Latinised name. For example, Syncerus (Sannazaro).

If there is one, what was the logic of the Latinisation of the name Louis as Aloysius? I mean, given my current little knowledge of Latin, works with "y" and "k" tend to be mainly of Greek origin. So it seems rather unatural to translate a name with a "y", even more if the original did not have it. What was wrong with Aloisius? It seems "oi" is actually a diphthong, whereas "oy" is not.

  • 5
    For what it's worth, this page derives the Latin form from an Occitan version Aloys. (I don't know how to explain the initial A-.)
    – TKR
    Apr 28, 2017 at 21:12
  • 2
    @TKR A or no A, I am fairly certain that you are correct. If there's any answer at all, that should be it. That said, I do wonder about that initial A. Perhaps it was assimilated to a similar-sounding name from the region. Très étrange.
    – cmw
    May 3, 2017 at 4:35

3 Answers 3


It seems that the Latin form Aloysius is based specifically on an Occitan form of the name, Aloys. The Latin has simply retained the Occitan spelling; I don't know enough about Occitan to say anything about that spelling, or about the strange initial A-.

  • 1
    The latter question might get a good answer in Linguistics.SE or even French.SE.
    – cmw
    May 3, 2017 at 22:44

It seems there are two possible etymologies for the Occitan name Aloys, whose Latinisation gave rise to the form Aloysius:

  1. cognate with German Ludwig, from Germanic (Frankish) name, a compound of (h)lūt ("fame") + wīg ("warrior").
  • Dutch Lodewijk
  • French Louis
  • Spanish Luis
  • English Lewis
  1. cognate with German Alwis, from Old High German al ("wholeheartedly") + wîsi ("wise, knowing").
  • English Elvis
  • Occitan Aloys
  • French Aloïs

If the second etymology is correct, that would explain the initial A-.

As for the y, though unusual, it is not unprecedented in Latinised Greek names. Modern names descended from those suffixed -ysius / -ysia tend to end in -is(e), so it seems reasonable to assume that Aloysius was back-formed from Aloys by analogy to these:

  • Dionysius > Dennis, Dion
  • Dionysia > Denise
  • Aloysius < Aloys
  • 3
    +1 for mentioning the Alwis etymology. Dec 19, 2017 at 15:29

I have read that the Latin suffix "ius" added to a surname between the Late Middle Ages and the Early Renaissance period of Europe originally indicated a man of scholar, much like Ph.D. is used today. Over time, the separation between the surname and the "ius" disappeared and became all one word. In Lithuania, the suffix "ius" is said to mean "son of".

  • 1
    Thanks for your answer. Do you have a source you could link to concerning this meaning of the "-ius" ending? Many Roman names end in -ius without this meaning, e.g. Appius, Lucius, Servius, Tiberius, etc. EDIT: I see now that you said "surname." But that wouldn't apply to "Aloysius," right?
    – brianpck
    Jul 9, 2020 at 18:25
  • That is an interesting observation. It makes me think immediately of Nicolaus Stenonius. I always thought of his ius ending as an adjectival one, taken from his father's name (presumably Steno / Stenonis). When Stenonius wrote his academic works, he needed a Latin name, and so he coined his from his father's name. In fact, he could have used his father's name simply as a genitive, and he did do this at least once Nicolaus Stenonis. Of course, ecclesiastics, nobles, and academics all needed Latin names, and Stenonius wasn't an ecclesiastic (yet) nor a noble.
    – Figulus
    Jul 10, 2020 at 14:07
  • So getting a Latin name if you weren't a noble would have been something like a rite of passage, either into the church, or into the academy.
    – Figulus
    Jul 10, 2020 at 14:09
  • Wherever you read that in wasn't a good source. That's exactly like saying that the suffix "-s" in English names like Jones originally indicated a manual labourer. The logic is that of an 8 years old: scholars/manual labourers typically have a name like that, therefore it indicates scholars/manual labourers. In reality -ius is nothing more than an generic Latinisation suffix extended from the many Roman names that have it. It originally stood for a relative adjective, largely equivalent to the English "-s". Jul 11, 2020 at 16:32

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