O'Shaughnessy
An Irish surname from a powerful Gaelic sept once associated with territory between Galway and Clare.
The #9,940 most common surname in the United States (2010 Census) — about 1 in every 95,116 Americans shares it.
Etymology
O'Shaughnessy is the anglicized form of an Irish Gaelic surname. The initial O' marks descent from an ancestor, and the second element comes from a Gaelic personal name traditionally rendered as Seachnasach or a related form, often explained as meaning something like "neglectful" or "careless" in older etymological treatments. The surname therefore began as a family-name indicating descent from a named forebear rather than from an occupation or place.
History
Historical sources place the O'Shaughnessy sept in a mountainous district between Galway and Clare, where they held land and local power. The name appears in medieval Irish records, and later spelling varies with English-language anglicization. It remains a distinctly Irish surname, though it is now found well beyond Ireland through emigration.
Origin
Regions
Variant spellings
Fun fact
Lower’s 19th-century account links the sept to a cross-border district between Galway and Clare, a reminder that many Irish surnames are tied to old Gaelic territories rather than modern county lines.
From the historical record
“the XIII. cent. D'Alton. OSHAUGHNESSY. "The O'Shangh- nessys were lords of a mountainous district dividing Galway from Clare. The sept is traced however, in the annals of other parts of the country." The surname first appears in 1060. D'Alton. O'SHEE. The pedigree is traced to Odanus O'Shee, lord of the cautred of…”
— Patronymica Britannica: a dictionary of the family names of the United Kingdom