Gauss wrote in his Ph.D. dissertation:
Si quis e. g. in art. 3, aliaque incognitarum tamquam cognita spectata, reliquas per hanc et coefficientes datos rationaliter exprimere tentat, facile inueniet, hoc esse impossibile, nullamque quantitatum incognitarum aliter quam per aequationem m-1ti gradus determinari posse.
What does the ti mean?
I suppose the obvious answer is that it's an exponent consisting of two variables, t and i, multipled together. But that doesn't look right. It's strange to raise 1 to an exponent, though with complex numbers that could produce a result other than 1. But, at least on a cursory look, I don't see variables t and i defined nearby. And I see ti used unitalicized and unsuperscripted, apparently as a suffix, here:
Facile vero perspicitur m′ fore numerum formae 2n-1i′, designante i′ numerum imparem. Iam nisi m′ est impar, supponatur iterum, uu+uu′+M′ esse diuisorem ipsius U, patetque per similia ratiocinia u′ determinari per aequationem U′=0, vbi U′ sit functio (m′ . m′-1) / (1 . 2)ti gradus ipsius u′.
Is it an ordinal suffix, enabling the mathematical expression to modify gradus? Or maybe a cardinal case suffix? If so, what else in Latin is it modeled after? All I can think of is big cardinal numbers like ducenti, trecenti, etc. (and viginti).
Huic incidi nexum sequens in hoc responso Ionæ Ilmavirta.