Definition of "alloy"

alloy¹

/ˈæ.lɔɪ/

noun
countable and uncountable, plural alloys
1. A metal that is a combination of two or more elements, at least one of which is a metal, a base metal.
2. (archaic) A metal of lesser value, mixed with a metal of greater value.
  Quotations
  Many of these coins are preserved at the British Museum, in London, and at the Ashmolean Museum, in Oxford, and are all of pure gold, without alloy, and in a good state of preservation. Boadicea, Queen of the Iceni, is also said to have […]
  1888, Arthur Talbot Vanderbilt, Gold Not Only in Wales, But Also in Great Britain and Ireland: Facts and Figures, page 17
3. An admixture; something added which stains, taints etc.
  Quotations
  Metrodorus said that in sadnesse there is some aloy of pleasure.
  1603, Michel de Montaigne, chapter 20, in John Florio, transl., The Essayes […], book II, London: […] Val[entine] Simmes for Edward Blount […]
  The sole grievance and alloy thus removed in the prospect of Harriet’s welfare, she was really in danger of becoming too happy for security.
  1815, Jane Austen, Emma, volume III, chapter 18
4. (figurative) Fusion, marriage, combination.
  Quotations
  SETH KITANGE TELEVISION AND RADIO Upheaval at CBS. […] Bill Moyers, a CBS News commentator and special correspondent, expressed his dismay in an interview with Newsweek in which he said, “Television news has never been pure. It has always been an alloy of journalism and show business.”
  1986, 1987 Year Book

alloy²

/əˈlɔɪ/

verb
third-person singular simple present alloys, present participle alloying, simple past and past participle alloyed
1. To mix or combine; often used of metals.
2. To reduce the purity of by mixing with a less valuable substance.
3. (figurative) To impair or debase by mixture.