A hollow nodule or pebble of hydrated iron oxide containing a loose kernel that makes a noise when rattled, formerly regarded as having medicinal and magical properties; the eagle stone; = "achate", "perdicle".
Late 15th century. From Anglo-Norman etite, Anglo-Norman etites (12th or 13th cent.; Middle French, French aétite, French †aetites, attested from 1577 to 1771, French †étite (attested from 1752 to 1842)) and its etymon classical Latin āetītēs (in lapis āetītēs eagle stone (Pliny); in post-classical Latin also without lapis) from Hellenistic Greek ἀετίτης (in ἀετίτης λίθος eagle stone) from ancient Greek ἀετός eagle + -ίτης. So called as the stone was said to be found in the eagle's nest.