Declension of Latin nouns or phrases in German

Question

When using Latin nouns or phrases in a German text, what is the best practice to decline them?

Take, for example, the word Col­le­gi­um mu­si­cum, which is to be declined as follows:

das Collegium musicum; Genitiv: des Collegium musicum, Plural: die Collegia musica (Duden)

Yet, it seems to be that in earlier times, the correct Latin genitive was used: des Collegii musici (cf. this)

It seems somewhat strange that it has retained its Latin plural, while the genitive was abandoned in favor of a germanized version. Same with Verbum: „das Verbum; Genitiv: des Verbums, Plural: die Verba“ (also Duden).

Would it be deemed a too old-fashioned way of expression to use the Latin declension, or do you think this could be acceptable, for example in an academic context?

Answer 1

In most cases it is really simple:

You are almost NEVER forced to use any other grammar but German grammar when terms from foreign countries are embedded in German sentences. Otherwise you had to learn the grammar from every language of the world to build proper german sentences including foreign terms.

A few examples:

The word "Kimono" is from Japanese language. In a german sentence you can build the plural or the accusative of it without learning Japanese: "In meinem Schrank hängen zwei Kimonos. Ich habe den Kimono zur Wäsche gegeben."

The word "Safari" is from Suaheli language. You can build correct german sentences with this word without any knowledge of Suaheli: "Franz will an einer Safari teilnehmen."

"Hobby" and "Baby" are english words. So in German sentences you have to decline them according to German rules: "Anna hat zwei Babys (NOT Babies!!) bekommen. Eines ihrer Hobbys (NOT Hobbies!!) ist Stricken."

BUT...

... there are some exceptions for latin words.

Der Leib Christi (not "der Leib Christus"). (latin: "corpus christi")
In Salzburg und Wien stehen zwei berühmte Collegia musica (not Collegiums musicum)

Declination of latin words in german sentences is tricky. Sometimes you have to use German grammar and sometimes Latin Grammar. It is really hard to tell when you have to use which grammar. The best way is to do what german native speakers do: Look it up in a dictionary. In doubt use German grammar.

A famous example:
The latin plural of the word "status" is "status" (the rule is named "u-declination") and in German you can use "die Status" as plural of "der Status" ("Vier verschiedene Status können einen Alarm auslösen"). But there are more latin words ending with "-us" who's plural ends with "-i" (dominus - domini). Since only few german speaking people know latin grammar many of them tend to build the wrong plural "Stati" ("Vier verschiedene Stati ..."). They would have done better if they had used german grammar ("Vier verschiedene Statusse ...") because "Statusse" is also a correct variation of the plural of "Status".

Answer 2

By and large, German declination is used, in particular if there is a loan word, like Kollegium in your example. Only occasionally will you hear somebody use the "correct" Latin declination, and then usually in a professional (legal, e.g.) or academic context.

Lawyers might say something like "der Brief Doktoris Mueller" (the letter of Dr. Mueller) or "die Kanzlei Doktores Mayer" (the law office of Dr. Mayer and Dr. Mayer), but even there is a real danger of coming off as a pretentious douche.

It's not normally used, except perhaps in some fixed expressions: "In Christi Namen" (in the name of Christ) might be used, or perhaps "durch die Gnade Jesu" (by the grace of Jesus), but apart from that? Don't use it. The same is usually true for the plural, really. The plural of Kollegium is Kollegien.

Your example is a bit of an exception; it's not just a word, it's almost a Latin phrase, perhaps tempting people to show off their classical education :) Isn't it pretty much the same in English? Would you use "stadia" to refer to more than one stadium?

Answer 3

As Ingmar's answer already covers the usage in current times, I want to lose a few words on why the Latin declension was used in earlier times.

Even until the early 18th century, Latin was the language of choice for academic purposes. The wikipedia article in German wikipedia has some nice information on that too:

Generationen von Kindern lernten seit 1658 Latein mit dem Orbis sensualium pictus, dem berühmten deutsch-lateinischen Bilderbuch des großen Pädagogen Johann Amos Comenius.

Mit dem Erstarken der Nationalsprachen seit dem 17. Jahrhundert verlor Latein mehr und mehr an Boden. In Deutschland erschienen im Jahre 1681 zum ersten Mal mehr Bücher auf Deutsch als in Latein.

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Generations of children since 1658 learned latin with the "Orbis sensualium pictus", the German-Latin picturebook written by the pedagogue Johan Amos Comenius.

When the national languages began to emerge in the 17th century, Latin lost importance. In 1681 in Germany the number of published books in German for the first time exceeded the number of books published in Latin.

_{Translation by me, full article behind this link}

This explains why at that time, more people (or rather those that were able to write) used the correct Latin declension, instead of the "incorrect" German.

Small additional fact: The Wikipedia article also mentions that even in 1830, Theoria colorum physiologica by Arthur Schopenhauer was published in Latin.