Dempsey
An Irish surname from O'Dempsey, originally a family name tied to an ancestral personal name or byname in medieval Ireland.
The #1,308 most common surname in the United States (2010 Census) — about 1 in every 11,493 Americans shares it.
Etymology
Dempsey is the anglicized form of the Irish surname O'Dempsey, written in Irish as Ó Díomasaigh. The name is usually explained as meaning “descendant of Díomasach,” from a personal name or byname associated with pride or arrogance. Older authorities sometimes handled the form differently, but the Irish origin is the standard explanation.
History
The name is strongly associated with Ireland and appears in historical surname lists in several spellings, including O'Dempsey and Dempsey. It became established as an anglicized surname and is especially found in Irish records and in later English-language usage. In modern times it is a familiar Irish surname in both Ireland and the diaspora.
Origin
Regions
Variant spellings
Fun fact
Matheson’s early-20th-century Irish surname tables list Dempsey among the more recognizable Irish family names, showing how firmly anglicized forms had already taken hold.
From the historical record
“Avhile others have become extinct. DEMPSEY. See Q'Dempsey. DENHAM."^- See under Tredenbam. DENNISTON.* A correspondent assures me that the lands of Dauiel's-toun are so designated in early charters of the family. DEVENISIL* The surname Le De- veuys is of early introduction into Ireland. In 1302 Nicholas Deveueys…”
— Patronymica Britannica: a dictionary of the family names of the United Kingdom