rosetta
n. countablen. a key or tool that helps you understand something very difficult or mysterious. It is named after a famous stone that helped experts read ancient Egyptian writing.
n. a crucial clue or key that provides the means to decode or understand a previously inscrutable system or language. Derived from the Rosetta Stone, which enabled the decipherment of Egyptian hieroglyphs.
This new codebook is the rosetta for our encrypted files.
The discovery of the genetic code served as a rosetta for understanding how biological information is passed between generations.
In the history of linguistics, the basalt slab found in 1799 became the ultimate rosetta, bridging the gap between known Greek and the mysterious symbols of the pharaohs.
Often used metaphorically to describe a breakthrough discovery; frequently capitalised when referring to the specific historical artifact.