The story
From the Irish surname, Anglicized from Ó Caiside (“descendant of Caiside”), from cas (“curly-haired”).
Etymology from Wiktionary, CC BY-SA 4.0.
Cassidy
Today it means: A surname from Irish anglicized from Ó Casaide (“descendant of Caiside”). Caiside is a byname from Irish cas (“curly”) meaning “curly-haired”. Full definition →