Reilly

Meaning and origin

The last name Reilly originated from Ireland and is an anglicized form of the Gaelic surname Ó Raghallaigh or Ó Raghallaigh, meaning "descendant of Raghallach." The root of the name Raghallach comes from the Gaelic word "raghallaigh," which translates to "valiant" or "courageous." Reilly is a common surname in Ireland, particularly among those with Irish ancestry, and has spread to other English-speaking countries through migration and diaspora.

The longer story

The last name Reilly is a surname of Irish origin, and it is predominantly found in the United States, particularly in states with a significant population of Irish Americans. The name Reilly has multiple variations, including O'Reilly, Riley, and Ryley. It derives from the Gaelic surname Ó Raghallaigh, which means "descendant of Raghallach." The Gaelic name Raghallach is believed to come from the word "ragh," meaning "race" or "progeny," and the personal name "Allach," which may refer to a mythical folk hero or warrior.

The Ó Raghallaigh clan held significant influence and power in ancient Ireland, particularly in the areas of County Cavan and County Longford. The name Reilly originated as a patronymic surname, indicating descent from a male ancestor named Raghallach. As with many Gaelic surnames, the apostrophe was later dropped in anglicized versions of the name.

Irish surnames often have multiple anglicized variations due to historical and linguistic factors, and Reilly is no exception. The variations Riley and Ryley are common adaptations of the original Reilly surname. These variations arose primarily through regional accents and dialects, as well as the individual preferences of immigrants and their descendants.

Surname origins are rarely settled: one spelling can have several sources, and families often took a name for reasons nobody wrote down. Check it against the sources below before you rely on it.