Casi is a female name with American English pronunciation of KAY-see (/ˈkeɪsi/). It is a variation of the name Casey. The origin of Casi is Irish, deriving from the Gaelic surname Ó Cathasaigh, meaning "vigilant" or "watchful." Casi has been given to baby girls in Texas since at least 1971, with varying levels of popularity over the years. In recent times, it has not ranked within the top 1000 names for newborns in the state. Casi carries a sense of uniqueness and individuality while maintaining a connection to its Irish roots.