Fact
Etymology
From Latin "factum" (a thing done, a deed), the neuter past participle of "facere" (to do, to make) — the same root behind manufacture, factory, and fashion. A fact is literally something made or done; the word once meant simply an act or deed before it drifted toward "a true state of affairs."
noun · /FAKT/
Something that is the case, true independently of anyone’s opinion about it.
What it names
Use it for claims settled by how the world actually is — the shared ground an argument needs before interpretation can even begin.
Example
We can argue about what the numbers mean, but the number itself is a fact.
Related idea
Its foils are opinion and belief: a fact holds whether or not anyone accepts it, while an opinion is a judgment that can differ between reasonable people. The whole rhetoric of "alternative facts" trades on erasing this line — treating what one believes as if it settled what is.