Alert, vigorous, or pure
Kayci is a modern phonetic spelling of the Irish surname Casey, meaning alert or vigorous. It is also frequently used as a diminutive of Katherine, which carries the Greek meaning of pure. This specific spelling variation gained some traction in the late 20th century alongside similar names like Kaylee and Kacie.
Less common today
Kayci isn't in the latest US Top 1000. It last peaked at #1,859 in 1990.
American professional soccer player
US births per 5-year period, 1990βpresent (SSA data).