Recorded in several forms including Ranahan, Renihan, Renahan, and Ronaghan, this is an early Irish surname. It is a developed form of the pre 14th century Gaelic name O' Reannachain. The prefix O' indicates male descendant of, plus the personal name Reannachain, from reannach, meaning sharp or keen, and the diminutive suffix -ain, meaning little or son of. This gives the translation of 'The male descendant of the son of Reannach'. The surname is first recorded in the 16th century as shown below, and appears as Ronaghan in Petty's famous register now known as 'The census of Ireland' in 1659 during the 'reign' of Richard Cromwell. As such this name is listed amongst the principal names of the barony of Tiranny, in County Armagh. It would seem that the prefix O' was one of the 'casulties' of the spelling being changed from the Gaelic, having been dropped at an earlier stage. The spellings as Renehan, Renahan and Renihan are chiefly found in the Counties Cork and Tipperary, whilst examples of the name recording include the Reverend Doctor Lawrence Renehan (1797 - 1857) of County Tipperary. He was president of Maynooth College, whilst in the marriage records we have that of Catherine Ranahan and William Beere who were married at St. Pauls church, Cork, on July 27th 1846. The first recorded spelling of the family name is shown to be that of Teag Renaghan of Carlingford, County Louth. This was dated 1560 in the "Fiants" or Letters to the Chancery Authority. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.