Female first name (English): Casey, descendant of Cathasaigh; Old Irish (family name as first name); cathasaigh = alert; by a family named 'Ó Cathasaigh', meaning 'descendant of Cathasaigh', the name Cathasaigh means 'vigilant', as female name in use male first name (English): Casey, descendant of Cathasaigh; Old Irish (family name as first name); cathasaigh = alert; by a family named 'Ó Cathasaigh', meaning 'descendant of Cathasaigh', the name Cathasaigh means' vigilant '; as a female name in use