Sullivan surname meaning

Sullivan is the anglicized form of the Irish surname Ó Súilleabháin. The prefix Ó marks a descendant, so the surname belongs in the parent’s-name category even though the older personal name is difficult to translate with certainty. Irish spelling, pronunciation, and English recordkeeping gradually produced Sullivan and O’Sullivan, while the original diacritics are often absent in American documents. The name is strongly associated with Munster and with Irish migration, but a US Sullivan line still needs genealogical evidence before a specific county or branch can be assigned.