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quinquagenary

[kwin-kwah-juh-ner-ee, kwing-]
noun, plural quin·quag·e·nar·ies.
  1. a 50th anniversary.

Origin of quinquagenary

1580–90; < Latin quīnquāgēnārius containing fifty, equivalent to quīnquāgēn(ī) fifty each + -ārius -ary
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018