E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A native of Abdra, a maritime city of Thrace. The Abdertans were proverbial for stupidity, hence the phrase, You have no more mind than an Abderite. Yet the city gave birth to some of the wisest men of Greece: as Democrtos (the laughing philosopher), Protagras (the great sophist), Anaxarchos (the philosopher and friend of Alexander), Hecatæos (the historian), etc.