Ogham

Ogham (also ogam and ogom, /ˈɒɡəm/ OG-əm, Modern Irish: [ˈoː(ə)mˠ]; Middle Irish: ogum, ogom, later ogam [ˈɔɣəmˠ]) is an Early Medieval alphabet used primarily to write the early Irish language (in the "orthodox" inscriptions, 4th to 6th centuries AD), and later the Old Irish language (scholastic ogham, 6th to 9th centuries). There are roughly 400 surviving orthodox inscriptions on stone monuments throughout Ireland and western Britain, the bulk of which are in southern areas of the Irish province of Munster. The Munster counties of Cork and Kerry contain 60% of all Irish ogham stones. The largest number outside Ireland are in Pembrokeshire, Wales.

The inscriptions usually consist of personal names written in a set formula.

Many of the High Medieval Bríatharogaim (kennings for the ogham letters) are understood to reference various trees and plants. This interpretation was popularized by Robert Graves in his book The White Goddess; for this reason, Ogham is sometimes known as the Celtic tree alphabet.

The etymology of the word ogam or ogham remains unclear. One possible origin is from the Irish og-úaim 'point-seam', referring to the seam made by the point of a sharp weapon.