Plato's Cratylus is about language, specifically about names (onomata), a category that includes proper names, common nouns, adjectives, participles and infinitives. On first reading it may appear to be a somewhat arcane work almost half of which is devoted to a discussion of what appear to be far-fetched etymologies of Greek words. When properly understood, however, this apparently unprepossessing material serves an important philosophical purpose. As Plato's most focused discussion of language, the text should be useful for every student of his work, and should also be of interest to anyone interested in Greek thought, the history of semantics, or the philosophy of language.