| 释义 |
WordReference Random House Unabridged Dictionary of American English © 2024co•run•dum (kə run′dəm),USA pronunciation n. - Mineralogya common mineral, aluminum oxide, Al2O3, notable for its hardness: transparent varieties, as sapphire and ruby, are used as gems, other varieties as abrasives: often made synthetically.
- Tamil kuruntam; akin to Sanskrit kuruvinda ruby
- 1720–30
Collins Concise English Dictionary © HarperCollins Publishers:: corundum /kəˈrʌndəm/ n - a white, grey, blue, green, red, yellow, or brown mineral, found in metamorphosed shales and limestones, in veins, and in some igneous rocks. It is used as an abrasive and as gemstone; the red variety is ruby, the blue is sapphire. Composition: aluminium oxide. Formula: Al2O3. Crystal structure: hexagonal (rhombohedral)
Etymology: 18th Century: from Tamil kuruntam; related to Sanskrit kuruvinda ruby |