Scanlon is an Anglicized form of the Irish Gaelic name Ó Scannláin, meaning "descendant of Scannlán",[1] and is a variant of the name Ó Scannail derived from the Irish word scannal, originally meaning quarrel, contention, fight, and later, scandal.
[2] There are three quite distinct septs or clans, the first and primary sept being the Ó Scannail (Scannell) (originally Scannal), who belong to West Munster and specifically the Counties of Kerry, Cork, and Limerick.
One sept is O'Scannlain of Munster and the other is McScannlain of Oriel, County Louth, neither of which has retained the prefix 0 or Mc in modern times.
The widespread distribution of these names is indicated by the fact that there are six Ballyscanlans in Ireland as well as a Scanlansland and a Scanlan's Island.
Two of these are in County Clare and one in Mayo, which lends colour to the statement that there was also a North Connacht Sept of O'Scanlan.