A diminutive of the female given name Cynthia and Lucinda; also used as a formal female given name.
"Cindy smiled warmly when her friends greeted her by her chosen first name rather than calling her Cynthia or Lucinda."
Cindy began as a shortened version of names like Lucinda and Cinderella before becoming an independent nickname for Cynthia in the 20th century. This popular pet name traveled into English usage during that era, shedding its original association with fairy tales to stand alone as a friendly form of Cynthia.