corundum
/kəˈɹʌn.dəm/ noun
Forms corundums
- noun (mineralogy) An extremely hard mineral, a form of aluminum oxide with the chemical formula Al₂O₃, that occurs in the form of the gemstones sapphire and ruby; it is used as an abrasive.
Synonyms
Etymology
From Tamil குருந்தம் (kuruntam, “ruby, sapphire”) First attested in the early 18th century.
Webster’s 1913
- noun The earth alumina, as found native in a crystalline state, including sapphire, which is the fine blue variety; the oriental ruby, or red sapphire; the oriental amethyst, or purple sapphire; and adamantine spar, the hair-brown variety. It is the hardest substance found native, next to the diamond.
Etymology [From Hind. kurand corundum stone.]
Sources: Wiktionary · WordNet 3.0 · Webster’s 1913 — from the Wiktionary entry “corundum”, CC BY-SA 4.0. Details