Recorded in several spellings including O' Conaghan, Conaghan, Connagon, Connahan, and Connachan, this is a surname of Irish origins. It is one of the many Irish surnames which derive from the pre 10th century Gaelic word 'conn' meaning a hound. These include surnames such as Conamy, Conomy, Connelly, Conley, Connick, and many others. The hound was a highly prized heraldic symbol in ancient times, and as such was a 'nickname' given to many early chiefs of the different clans and septs as an acknowledgement of their strength, speed or thought and action, and general toughness. In this case the clan are very rare. In general they are found as Conaghan in the area of County Donegal and sometimes Derry in Ulster, where many over the centuries have changed or perhaps more likely, have had their name changed, to the similiarly sounding 'Cunningham'. This has been a fate of many names particularly in the USA, and certainly not just Irish, that at various times in history the spelling has been transposed to a form, with which the registry clerks were more familiar. Early examples of the surname spelling are rare, mainly because the relevant registers were destroyed when the IRA burnt down the Public Records Office in Dublin, during the Civil War of 1922 - 1926. However some that survive are those of John Connagon at Hammersmith Roman Catholic church, London, on December 11th 1831, and in Scotland that of Joseph Connachan, whose birth was registered at Central District, Glasgow, on July 7th 1866.