What does it mean by acta?

Question

There are a lot math journals with title "acta" includes, for instance, Acta Mathematica, acta arithmetica, etc. Would you explain what "acta" means?

Answer 1

Acta is the plural of actum, a Latin word refering to $($official$)$ papers or documents.

Answer 2

In latin, $actum$ means $fact$ and $acta$ is, in latin, the plural form of $actum$.