Piece turned to compress two gases in forming diamond

• Famous diamond
• One of the British crown jewels

Wikipedia Word definitions in Wikipedia
Kohinoor commonly refer to Koh-i-Noor , a 105.6 metric carats diamond, weighing 21.6 gms, once the largest known diamond. Kohinoor may also refer to:

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Kohinoor \Koh`i*noor"\, Kohnur \Koh`*nur\ (k[=o]`[i^]*n[=oo]r"), n. [Per. koh-i-n[=u]r, lit., mountain of light.] A famous diamond, surrendered to the British crown on the annexation of the Punjab. According to Hindu legends, it was found in a Golconda ...