The name Kailey is an English feminine name derived from the Gaelic name Cailin, which means "girl" or "young woman." It is a variant spelling of the more common name Kaylee or Kayleigh. The name's origins can be traced back to the medieval Gaelic language spoken in Scotland and Ireland.

Cailin was originally a Scottish and Irish term used as a general description for a young woman or girl, rather than a formal given name. It gained popularity as a first name in the late 20th century, likely due to the increasing trend of using traditional Gaelic names in English-speaking countries.

The earliest recorded use of Kailey as a given name is relatively recent, with records showing it appearing in the late 20th century. However, the name's roots in the Gaelic language and culture date back several centuries.

Throughout history, there are a few notable individuals who have borne the name Kailey or its variants. One such person is Kailey Lafreniere (born 1990), a Canadian former competitive figure skater who represented Canada at the 2010 Winter Olympics in Vancouver.

Another notable Kailey is Kailey Kurachenski (born 1992), a Canadian former competitive swimmer who specialized in the breaststroke events. She won a bronze medal at the 2010 Commonwealth Games in Delhi, India.

In literature, Kailey is the name of a character in the young adult novel "Fade" by Lisa McMann, which was published in 2009. The book follows the story of a teenage girl named Janie who has the ability to become invisible.

Kailey Musso (born 1995) is an American actress known for her roles in the Disney Channel series "Wizards of Waverly Place" and the Nickelodeon series "Sam & Cat."

Lastly, Kailey Roberts (born 1975) is a Canadian country music singer and songwriter. She has released several albums and has had several charting singles on the Canadian country music charts.

While the name Kailey is relatively modern, its roots in the Gaelic language and culture give it a rich historical significance, and its increasing popularity in recent decades has led to its association with notable individuals across various fields.