The name Casey is of Irish origin, derived from the Gaelic "Cathasaigh," which means "alert" or "vigilant." It is traditionally a male given name, though it can also be used for females. In the United States, Casey gained popularity in the mid-20th century and was among the top 1,000 names for boys during much of that period.
"The name Casy saw its peak popularity between 1980 and 1986, with the highest number of births occurring in 1985 at thirteen. However, it seems to have been less common after 1999."