noun

• (phonology) A phonological process found in many dialects of English, especially American English and Canadian English, by which intervocalic /t/ and /d/ surface as the alveolar flap [ɾ] before an unstressed syllable, so that words such as "metal" and "medal" are pronounced similarly or identically.
• (computing, telecommunications) The situation where a resource, a network destination, etc., is advertised as being available and then unavailable (or available by different routes) in rapid succession.
• (uncountable) The unlicensed racing of horses or greyhounds.
  "Greyhound racing had its origins in whippet racing, which was derived in turn from hare coursing. By the early twentieth century, however, a form of dog racing held in 'flapping tracks' was a common pastime in the wastelands near working-class areas of industrial cities."