virtute de regno certam

Hello all. I’m trying to figure out the motto for my school. It is virtute de regno certam, but that’s not the word order. It’s written around a shield with de regno at the top; I assume that’s for emphasis. Anyway, I’m okay with the de regno and virtute, but the certam is throwing me. Why an accustaive adjective? I assume it is referring to the school name, which is feminine, but why accusative? My leading theory is that there must be an assumed subject and verb, as if these words were part of some saying, but just these words were placed on the school’s seal. However, I have no idea what the original sentence or saying might be. Any thoughts? Could certam be a shortened form?

If “certo” were a 3rd conjugation verb (it’s not), it could mean “I will fight with virtue for the kingdom”… but as is, “certam” is very ambiguous here…

my bad translation should be “the true virtue of the kindom”

That can’t work because ‘certam’ is accusative and ‘virtute’ is ablative, so ‘certam’ is not modifying ‘virtute’. This is interesting syntactically though. I’m assuming ‘virtute de regno’ means “by the virtue/strength of the kingdom” with ‘virtute’ being an instrumental ablative. ‘Certam’ is the one that seems to be just hanging there in the middle of the abyss. I looked through a Latin dictionary and ‘certam’ has to be the accusative singular feminine form of the adjective ‘certus’, it can’t be anything else. I’m with the hypothesis that it’s taken from a longer statement and whoever did it wasn’t familiar enough with Latin to realize that it makes a curious phrase on its own, or they didn’t care.

Have you asked anyone about it? I’m assuming that someone knows what the motto means, I mean it’s the school motto! If you find out make sure to let us know this is interesting.

The accusative can indicate an exclamation. Was yours ever, or is it, a girls-only college? Oh, the school name is feminine (just noticed). OK. It’s an exclamation, then, in my opinion.
Accusativus casus exclamationem indicare potest. Equando puellarum merè fuit collegium tuum? Modò animadverti nomen collegio femininum esse te dixisse. Licet. Justa tunc est exclamatio, ut opinor.