Main Entry: Ro·set·ta stone

Pronunciation: \rō-ˈze-tə-\

Function: noun

Etymology: Rosetta, Egyptian

Date: 1822

1 : a black basalt stone found in 1799 that bears an inscription in hieroglyphics, demotic characters, and Greek and is celebrated for having given the first clue to the decipherment of Egyptian hieroglyphics
2 : one that gives a clue to understanding