Lonergan
An Irish surname, likely from an old Gaelic byname or place-based form that later produced spellings like Londregan and Landregan.
The #8,817 most common surname in the United States (2010 Census) — about 1 in every 83,153 Americans shares it.
Etymology
This surname is generally treated as Irish in origin, with historical spellings showing a cluster of related forms such as Lonergan, Londregan, Landregan, and Ladrigan. The older sources suggest a Gaelic source-name behind the English spellings, but the exact original form and literal meaning are not fully secure from the excerpts alone. In short, it is an Irish surname whose early written forms varied considerably as they were rendered into English.
History
The surname is strongly associated with Ireland, especially Munster, and the nineteenth-century material places it in Cork. The historical census-style counts in the excerpts show it as a recognized Irish family name by the 1800s, with variant spellings still circulating. Later standardization settled mainly on Lonergan, though older forms such as Londrigan and Landregan remained in use in records.
Origin
Regions
Variant spellings
Fun fact
The historical sources group Lonergan with several look-alike Irish spellings, showing how fluid surname spelling could be before modern standardization.
From the historical record
“Lummacks. 72. LONERGAN. Ladrigan. 170. Landregan. 1086 LEFANU. Leycester. Londregan. 117”
— Varieties and Synonymes of Surnames and Christian Names in Ireland