why not modus operandus?
October 6, 2008 12:26 PM   Subscribe

[Latin filter] Why is it "modus operandi" and not "modus operandus"?

Can someone who took more Latin than I did explain why "modus" appears to be singular and "operandi" appears to be plural and yet they're always paired? Thanks.
posted by Capri to Writing & Language (8 answers total) 1 user marked this as a favorite
 
The i on operandi is for of.
posted by phunniemee at 12:31 PM on October 6, 2008


Like phunniemee said. Operandi is not nominative plural; it's genitive singular.
posted by phoenixy at 12:34 PM on October 6, 2008 [1 favorite]


Best answer: Because it's not "operation mode", it's "mode of operation". "Of" something makes it genitive case, and for 2nd (?) Declension singular, the ending is "i".

The nominative plural has the same ending, but if "operandi" were an adjective modifying a plural noun, "modus" would also be nominative plural, or "modi", and the phrase would be "modi operandi". But "operandus" isn't an adjective.

So we have a nominative singular "mode" and a gentive singular "operation", and it's "mode of operation".
posted by orthogonality at 12:37 PM on October 6, 2008 [1 favorite]


Orthogonality - you are correct, the '-us' endings are second declension.
posted by amicamentis at 12:46 PM on October 6, 2008


Isn't operandi the gerundive, hence "mode of operating", not "mode of operation"?
posted by sagwalla at 3:22 PM on October 6, 2008


Best answer: operandi is actually what is known as a gerund in Latin grammar. It's a way of converting a verb (to operate, to speak) into a noun (of operating, in speaking, etc.)

Now, gerunds don't actually appear in the nominative case. The form of the verb used if you want to say, for example, "making errors is characteristic of humans" is the infinitive. Errare est humani

The genitive of the gerund can limit an adjective or noun in some way:
vir bonus dicendi peritus
a good man skilled in speaking
difficultas navigandi
difficulty in sailing
cupiditas videndi deos hominesque
desire of seeing gods and men
Triste est nomen ipsum carendi
the mere word "to lack" is dismal
Et propter vitam vivendi perdere causas
And on account of life, to lose the reasons for living
Dissimulandi causa in senatum venit
He came to the senate for the purpose of dissimulation

Its other cases are used in some other circumstances - Lex est recta ratio in iubendo et vetando (the law is the right method in ordering and forbidding). There's a gerundive, which is an adjective which implies that someone is able, worthy or necessary of, for example, being loved or heard.

That answer was longer than I intended to write. I'll put away my language nerd hat and back away from the dictionary now.
posted by I_pity_the_fool at 3:36 PM on October 6, 2008 [1 favorite]


You forgot the best one, the neuter accusative gerundive of obligation: e.g., pudendum: "that of which one ought to be ashamed".
posted by felix betachat at 6:55 PM on October 6, 2008 [1 favorite]


i love latin! me delectat.
posted by alice ayres at 10:10 AM on October 7, 2008


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