Wikipedia
Cratylism as a philosophical theory reflects the teachings of the Athenian Cratylus (, also transliterated as Kratylos), fl. mid to late 5th century BCE. Vaguely exegetical, it holds that the fluid nature of ideas, words, and communications leaves them fundamentally baseless, and possibly unable to support logic and reason.
Cratylism reaches similar conclusions about the nature of reality and communication that Taoism and Zen Buddhism also confronted: how can a mind in flux, in a flowing world, hold on to any solid "truth" and convey it to another mind?
A fellow-Greek sophist, Gorgias, expressed an equally ironic cul de sac conclusion about the nature of human epistemological understanding:
"Nothing exists. Even if something did exist, nothing can be known about it; and even if something can be known about it, knowledge about it cannot be communicated to others. And, finally, even if it can be communicated, it cannot be understood."