Ogham

... is an Early Medieval alphabet, used to write the Irish language in the 1st to 9th centuries AD. There are about 400 surviving inscriptions on stone monuments throughout Ireland and western Britain, the bulk of which are in the far south of Ireland. The largest number outside Ireland are in Pembrokeshire.

The etymology of the word 'ogham' is unclear. One possible origin is from the Irish og–úaim ('point–seam'), referring to the seam made by the point of a sharp weapon.