A Diphthong With No Letter of Its Own

Eabhadh is the first of the five forfeda, the group of supplementary ogham letters added after the twenty core letters had already settled into use on stone. The original alphabet was built for Primitive Irish, and by the Old Irish period the language had developed diphthong sounds the twenty letters could not spell as a single character. Eabhadh was devised to carry one of these, a sound close to eo, so that a scribe copying a manuscript did not have to fall back on a two letter workaround for a sound speakers treated as one.

The Auraicept na n-Eces glosses Eabhadh with crithach, aspen, following the tree naming convention that gives the core alphabet its popular reading as a set of trees. Whether that gloss reflects a living naming tradition or a scholarly tidiness applied after the fact is not settled: the tree names of the original twenty letters are themselves argued over, and a supplementary letter invented centuries later inherits that same uncertainty rather than resolving it. What is not in doubt is the letter's job, filling a gap in the spelling system of a language that had moved on from the one the alphabet was first cut for. Eabhadh's position first among the five forfeda is itself a manuscript convention rather than a claim about when the sound gap opened, since the tracts that preserve the supplementary letters do not agree on a single fixed order for all five.

Sources Auraicept na n-Eces: The Scholars' PrimerGeorge Calder (ed.) with A Guide to OgamDamian McManus