E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
A religious order of Ireland and Scotland, said to have been founded in the sixth century by St. Columba. So called from the Gaelic cylle-dee (a house of cells) or ceilede (servants of God, ceile, a servant). Giraldus Cambrensis, going to the Latin for its etymology, according to a custom unhappily not yet extinct, derives it from colo-deus (to worship God).