Casey
An Irish surname most often understood as coming from a word for “vigilant” or “watchful,” though some older writers linked it to “valiant.”
The #504 most common surname in the United States (2010 Census) — about 1 in every 4,639 Americans shares it.
Etymology
Casey is generally treated as an anglicized form of Irish Ó Cathasaigh or related spellings, from the Gaelic personal name Cathasach. The name is usually explained from cathasach, meaning “vigilant,” “watchful,” or “alert,” built on cath, “battle.” Some 19th-century writers also glossed it more loosely as “valiant,” but the watchful/alert sense is the safer modern explanation.
History
The surname is strongly associated with Ireland and is especially common in several Irish counties, including areas of the midlands and southeast, though it also appears widely through emigration. In older Irish genealogical and surname literature, Casey is grouped with a number of anglicized Gaelic family names and variant spellings. A minority of early writers suggested non-Gaelic or alternative explanations, but the Irish derivation is the standard one.
Origin
Regions
Variant spellings
Fun fact
The playwright Seán O'Casey helped make the surname especially familiar beyond Ireland.
From the historical record
“Casement. FI. Casman ; a p.n. Casey. From the Irish cathaiseach (valiant). Or see Case Cashmore. From Cashmoor ; a loc. n., Dorset Cassell. A loc. n., Flanders”
— British Family Names: their origin and meaning (2nd ed.)