Forfeda

	Aicme Beithe		Aicme Muine
ᚁ	Beith	ᚋ	Muin
ᚂ	Luis	ᚌ	Gort
ᚃ	Fearn	ᚍ	nGéadal
ᚄ	Sail	ᚎ	Straif
ᚅ	Nion	ᚏ	Ruis
	Aicme hÚatha		Aicme Ailme
ᚆ	Uath	ᚐ	Ailm
ᚇ	Dair	ᚑ	Onn
ᚈ	Tinne	ᚒ	Úr
ᚉ	Coll	ᚓ	Eadhadh
ᚊ	Ceirt	ᚔ	Iodhadh
	Forfeda
ᚕ	Éabhadh
ᚖ	Ór
ᚗ	Uilleann
ᚘ	Ifín	ᚚ	Peith
ᚙ	Eamhancholl

The Forfeda are the "additional" letters of the Ogham alphabet, beyond the basic inventory of twenty signs. The most important of these are five forfeda which were arranged in their own aicme or class, and were invented in the Old Irish period, several centuries after the peak of Ogham usage. They appear to have represented sounds felt to be missing from the original alphabet, maybe é(o), ó(i), ú(i), p and ch.

The five aicme forfeda are glossed in the manuscripts Auraicept na n-Éces ('The Scholars' Primer), De dúilib feda ('Elements of the Letters') and In Lebor Ogaim ('The Book of Ogam'), by several Bríatharogaim ("word oghams" ), or two word kennings, which explain the meanings of the names of the letters of the Ogham alphabet. Three variant lists of bríatharogaim or 'word-oghams' have been preserved, dating to the Old Irish period. They are as follows:

Later Medieval scholars believed that all of the letter names of the ogham alphabet were those of trees, and attempted to explain the bríatharogaim in that light. However, modern scholarship has shown that only eight at most of the original twenty letter names are those of trees, and that the word-oghams or kennings themselves support this. Of the forfeda letter names, only one may be that of a tree or shrub (pín) and their kennings as edited (in normalized Old Irish) and translated by McManus (1988) are as follows:

Four of these names are glossed in the Auraicept with tree names, ebhadh as crithach "aspen", oir as feorus no edind "spindle-tree or ivy", uilleand as edleand "honeysuckle", and iphin as spinan no ispin "gooseberry or thorn".

The kennings for Ébhadh point to the sound éo or é, which is also the word for "salmon". The name appears modelled after Eadhadh and Iodhadh. The kennings for Ór point to the word ór "gold" (cognate to Latin aurum). The kenning of Uilleann, "great elbow", refers to the letter name. Since the Ogham alphabet dates to the Primitive Irish period, it had no sign for [p] in its original form and the letter Pín was added as a letter to express it. McManus states that the name Pín was probably influenced by Latin pinus ('pine'), but a more likely explanation is that it derives from Latin spina ('thorn'), as the kennings indicate a tree or shrub with sweet tasting fruit (therefore not a pine). According to Kelly (1976) the name spín ( deriving from the Latin ) appears in the Old Irish tree lists as meaning either gooseberry or thorn, so the medieval glosses may be correct on this occasion. The name Eamhancholl means "twinned C", referring to the shape of the letter. The Bríatharogam kenning "groan of a sick person" refers to a value ch [x], predating the decision that all five forfeda represent vowels.

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Wikipedia