[OIr., bloody crescent, crook], also known as Cenn Crúaich, etc. [bloody head, chief (?); lord of the mound (?)].
The chief idol of pagan Ireland as described in Christian accounts of pre-Patrician history. It was thought to stand in Mag Slécht [the plain of adoration or prostrations], in Co. Cavan, near the present village of Ballymagauran; often associated with the Killycluggin Stone from Cavan, now in the National Museum, Dublin. The central idol was gold, surrounded by twelve others of stone. First worshipped by a shadowy king known as Tigernmas, Crom is described as the principal god of every Irish people before the coming of St Patrick. To him was sacrificed on each Samain the first-born of every family and the first-born of every livestock.
Although St Patrick and other evangelists are described as smashing stone idols, the latter are not always named as Crom Crúaich. The portrayal of the cruel idol demanding human sacrifices may be an echo of the scriptural accounts of Tophet and Moloch, as Eoin MacNeill has suggested. Nevertheless, certain stones are still accorded magical powers in isolated parts of the Celtic world. The name ‘Crom’ lends itself to a mild oath, comparable to ‘by Jove’ or ‘by Jingo’, in both spoken Irish and English. In oral tradition Crom Crúaich was euhemerized to Crom Dubh. The smashing of the idol is associated with both the last Sunday in July and the first Sunday in August, called the Lughnasa, Garland Sunday, or Domhnach Chrom Dubh.