The things that are given. Facts handed over as the ground a reckoning stands on, before anything is concluded from them.
Latin data, plural of datum (a thing given), past participle of dare (to give); the things handed over as given, the ground a reckoning stands on before anything has yet been concluded from them.
Latin dare is to give, and the word never stopped meaning that: data is what has already been handed over, before any conclusion has been drawn from it. Calling something data is a claim about its origin, not yet about what it proves.