The antonyms for the word "most unattested" can be easily found by considering its meaning. Unattested means something that cannot be proven or verified, therefore, the antonyms will be words that express proof, verification, or support. The opposite of unattested may be "verified," "supported," "confirmed," "validated," "proven," "attested," "established," "authenticated," "substantiated," and "evidenced." These words denote something reliable, trustworthy, and proven, unlike the original word. By using these antonyms, we can convey a sense of certainty and validity in our statements, which is essential in various contexts, such as legal or academic settings.