Rosetta stone

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.

Rosetta stone

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

Rosetta stone

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.

Notes

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

Example Sentences

What registers on her face as she lists each disliked item is a baseline, a Rosetta Stone.

From Salon

It really was like finding the Rosetta Stone of my life.

From Salon

You mean to tell me that we have recondite, intricate rules boobytrapping our finances that require a specialized degree or a Rosetta Stone to interpret, and interpreting them incorrectly could lead to ruinous fines, prison or both?

From New York Times

In a years-long quest, the American news media continues to send its journalists out into the heart of red state America with the goal of discovering some supposedly hidden and mysterious truth – a Rosetta Stone of sorts – for understanding the collective political insanity of the Age of Trump and the enduring power of its leader.

From Salon

"This discovery was similar to stumbling upon the Rosetta Stone in terms of genetics," Johnston explained.

From Science Daily