opal

plural opals

1. chemistryA mineral consisting, like quartz, of silica, but inferior to quartz in hardness and specific gravity, of the chemical formula SiO₂·nH₂O.

   Although there are dozens of different types of gems, among the best known and most important are […] . (Common gem materials not addressed in this article include amber, amethyst, chalcedony, garnet, lazurite, malachite, opals, peridot, rhodonite, spinel, tourmaline, turquoise and zircon.)

   2012 March 28, Lee A. Groat, “Gemstones”, in American Scientist, volume 100, number 2, archived from the original on 14 Jun 2012, page 128

   1. chemistryA precious gem, an iridescent gemstone found in the opal-silica mineral substrate (potch)
2. The colour of opal: any shade of blue with bright flecks of other colours, such as white, yellow, and red.

   The witchery of the dawn turned the grey river-reaches to purple, gold, and opal; and it was as though the lumbering dhoni crept across the splendors of a new heaven.

   1889, Rudyard Kipling, “Only A Subaltern”, in Under the Deodars, Boston: The Greenock Press, published 1899, page 141

3. biochemistryA colloquial name used in molecular biology referring to a particular stop codon sequence, "UGA."
4. Any of various lycaenid butterflies of the genus Nesolycaena.

1. A unisex given name from English from the precious stone, invented in the nineteenth century.

   Perhaps to console herself for the bad luck she had already suffered, in a back corner of South Sherbrooke Township - or perhaps to make up, ahead of time, for a lack of motherly feelings - she gave the girls the fanciest names she could think of: Opal Violet, Dawn Rose, and Bonnie Hope.

   1985, Alice Munro, The Progress of Love, Chatto&Windus, published 1987, →ISBN, page 208

   1. A female given name from English from the precious stone, invented in the nineteenth century.
   2. rareA male given name from English from the precious stone, invented in the nineteenth century.
2. AustraliaA type of petrol made by British Petroleum designed to be unable to be used for petrol sniffing.First known use Developed 2005.

   2 more examples

   Halton says, for example, that if there are bylaws that prohibit trafficking in fuel in a community where the non-sniffable petrol, Opal, had been introduced it would be the job of the local police to enforce the law. Her department, on the other hand, was dealing with the issue of the availability of Opal.

   2006, Paul Malone, Taking the ‘Hospital Pass’ – Jane Halton, Department of Health and Ageing: Australian Department Heads Under Howard - Career Paths and Practice, page 131

   Diesel is available at roughly 300km intervals on the WA side, as is Opal fuel which, at the Warburton and Warakuna roadhouses, can be used instead of unleaded petrol. (Opal is unsniffable, and its provision is one of the measures in place to counteract petrol-sniffing problems in local communities.)

   2007, Terry Carter, Lara Dunston, Perth & Western Australia, Lonely Planet, page 163

3. A hamlet in Alberta, Canada.
4. A census-designated place in Virginia.
5. A town in Wyoming.