"Lenihan" is an Irish surname. Variants include "Lenighan”, "Lenegan", "Lenaghan, “Lenahan”, and "Lennihan." People with the name include:
A Roscommon family of this name, in Irish O Leanachain, appears in early records, the most notable of whom was Maelciaran O'Lenechan of Tuamna, in Boyle barony, a priest very highly praised in the "Annals of Loch Ce" and by the Four Masters for his numerous good qualities: he died in 1249. Little is heard of them in modern times. Kinehan or Lenihan as it is also spelt, is now regarded as belonging primarily to Counties Limerick and Tipperary. Maurice Lenihan (1811–1895), author of the History of Limerick, is the most notable bearer of the name.
Lenihan, Lenehan, Lenahan, and Linehan are anglicized versions of the Irish Ó Leanachain, possibly from leanach, meaning "sorrowful". It appears to have arisen separately in two localities, in County Roscommon in the west, and in the south in the Limerick/Tipperary region. Bearers of the surname are found in both areas today, but it is most common in the south. Although born in Waterford, Maurice Lenihan (1811–1895) is closely associated with his adopted city of Limerick. A campaigning nationalist journalist, he was editor and proprietor of the Limerick Reporter for more than 40 years and is now best remembered as the author of Limerick: Its History and Antiquities (1860). The most prominent contemporaries of the name are Brian Lenihan (1924–1992) and his younger sister Mrs. Mary O'Rourke, of the Roscommon family, who both served in a variety of ministerial positions in the Irish government from the 1970s through to the 1990s.
Lenaghan Quite numerous: Down etc. See Lenihan. Leneghan rare: Mayo, Down. See Lenihan. Lenehan numerous: Midlands, Mayo-Sligo etc. See Lenihan. Lenihan numerous: all areas except Ulster, mainly Kerry-Clare-W Limerick-Cork. The Irish is (1) Ó Leannacháin (2) Ó Luingeacháin. The former relates to a Roscommon sept; the latter to Munster and comes, according to Woulfe, from earlier Mac Longacháin where longach may be gluttonous, avid. Note the variants. IF & SGG. Ó Leannacháin Lenihan: líon beag: Connachta & Lár na Tíre. Clann ó Ros Comáin go bhfuil athleagain Ó Léanacháin & Ó Lionacháin orthu. Féach Ó Loingeacháin & Ó Longacháin, leis. Féach Mac Leannacháin thuas