The Gilbert Sept of the Clan Buchanan

Gibb, Gibbon, Cubbin, MacCubbin, Gibson, Gilbert, Gilbertson, MacGibbon and Gibbons.

Gilbert was the name of the seventh Laird of Buchanan and it was he who assumed the surname of Buchanan. 

Buchanan of Auchmar, in his account of the Buchanans of Miltown, Chasill, Ardwell, etc., says that the MacGilberts and Gilbertsons are descended from the Buchanans of Sallochy. Their progenitor, whose name was Gilbert, was an immediate cadet of the family of Buchanan.  Unfortunately Auchmar neglects to tell us from which Laird this Gilbert was descended.  Gibb and Gibbon are diminutive (like a nickname) of Gilbert and Cubbin: MacGibbin, and Gibson are all variations of these names.  Of course, the prefix Mc or Mac or the suffix son or s can be added to any name.