Irish surname evidence

McDermott surname origin and Irish county evidence

The strongest processed county signals for McDermott include Cork, Antrim, Armagh. These are evidence clusters rather than proof that every McDermott family began in one place.

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Name history

What the historical record says

McDermott anglicises the Gaelic Mac Diarmada, "son of Diarmaid," a personal name read as "unenvious" or "free man." The family were the royal house of Moylurg in County Roscommon, styled MacDermot, and descend from Diarmaid, a great-grandson of the High King Maoileachlainn II. One of the great dynasties of Connacht, they held Moylurg for centuries, and the name remains strongly concentrated in Roscommon and the neighbouring counties of Sligo and Galway.

Recorded Gaelic root: Mac Diarmada

County evidence

Strongest county signals

  1. Corkprocessed surname/place signal
  2. Antrimprocessed surname/place signal
  3. Armaghprocessed surname/place signal
  4. Galwayprocessed surname/place signal
  5. Kildareprocessed surname/place signal
Read this carefully

What this evidence can—and cannot—prove

Census clustering can show where a surname appeared strongly at a historical point in time. It cannot identify your exact ancestor, prove a clan relationship, or assign a coat of arms. Use it as a source-backed starting point alongside family records and parish research.