Sheehan
An Irish surname, usually understood as an anglicized form of an old Gaelic personal name meaning “wise” or “courteous.”
The #1,305 most common surname in the United States (2010 Census) — about 1 in every 11,477 Americans shares it.
Etymology
Sheehan is generally taken from the Irish Gaelic surname O'Siadhachain, which is linked to a personal name built from siadhach, meaning “wise,” “courteous,” or “pleasant.” The name was later anglicized in several spellings, including Sheehan, Sheahan, Sheean, and Sheen. Some older writers also connected it with related Gaelic forms and treated Sheehy as a close variant.
History
Historical sources place the O'Sheehans as a sept in counties Cork and Limerick. The surname is well established in Ireland and appears in 19th-century Irish surname lists in substantial numbers. In English-language records it often appears without the prefix O'.
Origin
Regions
Variant spellings
Fun fact
19th-century Irish surname scholars often grouped Sheehan with several similar spellings, showing how fluid anglicization could be across records.
From the historical record
“SHEEAN "[(Celt.) i the Ir. Sdadhachan = SHEEHAN J Wise, Courteous [Ir. seadhach (dh mute) -|- the dim. suff. -an] 2 the lT.Sidheachan = Woi.T [Ir. sidheach (dh mute) -1- the dim. suff. -a'«] SHEED = Shead, q.v. SHEEL = Shiel, q.v. SHEEN (Eng.) i Bright, Fair \U.'S.. sheene,”
— Surnames of the United Kingdom: a concise etymological dictionary (2 vols in 1)