Mac Uallacháin
Mac UALLACHÁIN—IV—M'Coulaghan, M'Wolleghan, Coulahan, Coulihan, Colahan, Coolahan, &c.; 'son of Uallachán' (diminutive of uallach, proud, haughty); the name of an ancient and respectable family in Offaly. They are of the same stock as the O'Maddens, and were at one time chiefs of Siol Anmchadha; but for many centuries have been seated in the parish of Lusmagh, in Offaly, which originally formed part of Siol Anmchadha.
Alphabetical Index to Irish Surnames