Word for a guess that turned out to be correct? (Ex-conjecture)

In mathematics we have a problem. Unproven guesses are often referred to as "conjectures" – for example, the Poincaré conjecture, or the Tait conjectures. (Notable exceptions: the Riemann hypothesis, which gets the word "hypothesis" instead for some reason, and Fermat’s last theorem, which was called a "theorem" even before it was proven in 1995.) Sometimes, someone eventually proves these conjectures, turning them into theorems. Unfortunately, the name doesn’t get updated. Case in point: both the Poincaré conjecture and the three Tait conjectures have been proven, and yet we still call them "the Poincaré conjecture" and "the Tait conjectures" because that’s the name they’ve gone by for such a long time.

I find this situation less than optimal. The simplest solution would be to refer to them as "the Poincaré theorem" and "the Tait theorems", but this doesn’t let the reader know that these famous problems had a different name in the literature for a long time. It also wrongly implies that they were solved (proven) by Poincaré and Tait. I think the current standard is to use a phrase like "the Poincaré conjecture (now a theorem)", which is less a solution and more an apology for not having one.

My suggestion is to create a new, separate word that means "this used to be a conjecture for a while but it’s proved now". For example, let me invent the word accepture: the Poincaré accepture, the Tait acceptures. This simultaneously lets the reader know that (a) this used to have another name and (b) it’s now been proven. (If it’s been disproven: perhaps "rejecture" or "disjecture"?)

But it would be a lot nicer if there were an existing word I could use rather than having to invent my own word. One reasonable suggestion is "ex-conjecture" (or "exconjecture", since mathematicians like to leave out hyphens). But this doesn’t tell the reader if it’s been proven or disproven. So my question is,

Is there a word out there that means a guess that turned out to be correct, especially a guess that had been unresolved for a very long time?

(Disclaimer: I’m not a mathematician)