Rosetta stone

American  

noun

1. a stone slab, found in 1799 near Rosetta, bearing parallel inscriptions in Greek, Egyptian hieroglyphic, and demotic characters, making possible the decipherment of ancient Egyptian hieroglyphics.

2. a clue, breakthrough, or discovery that provides crucial knowledge for the solving of a puzzle or problem.

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Rosetta stone British  

noun

1. a basalt slab discovered in 1799 at Rosetta, dating to the reign of Ptolemy V (196 _bc ) and carved with parallel inscriptions in Egyptian hieroglyphics, demotic characters, and Greek, which provided the key to the decipherment of ancient Egyptian texts

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Rosetta stone Cultural  

1. A stone discovered in Egypt (see also Egypt) in the late eighteenth century, inscribed with ancient Egyptian hieroglyphics and a translation of them in Greek. The stone proved to be the key to understanding Egyptian writing.

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A “Rosetta stone” is the key to understanding a complex problem.

Example Sentences

It was a piece of advice he never forgot — the rosetta stone to everything that happened after.

From Washington Post • Jan. 31, 2015

But there are a lot of misconceptions about the universal form, which is the rosetta stone for college financial aid departments.

From Forbes • Jan. 14, 2015