Ogham Onn: the gorse letter, a name meaning ash, and its readings

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Onn, the seventeenth letter of ogham: a name meaning “ash”, yet linked by the manuscripts to gorse. What the sources say, and the modern reading.

Key points

Letter	Onn (ᚑ)
Rank	17th letter, Aicme Ailme (A group)
Sound value	o
Tree in the manuscripts	Gorse (aiten); the name nevertheless means “ash”
Meaning of the name	“ash”
Modern keywords	Gathering, abundance, tenacity

The letter Onn in the alphabet

Onn is the seventeenth letter of ogham, the second vowel: two notches on the baseline, for the sound [o]. It belongs to the aicme Ailme, the group of vowels, and follows Ailm.

It is an interesting case, because the name of the letter and the plant the manuscripts give it do not match. Here are the key facts:

Reference	Detail
Rank	17th of the 20 main letters
Group (aicme)	Aicme Ailme (A group): 2 strokes, notches or short strokes perpendicular to the baseline, used to write vowels
Sound value	o
Tree or plant in the manuscripts	Gorse (aiten); the name nevertheless means “ash”

The name and its meaning: what the sources say

Onn means “ash”: the word has a Welsh cousin, onn, and the ash tree supplies Europe with timber for tools, shafts and spears. In Old Irish this word was replaced by another (uinnius), which McManus sees as a sign that letter names go back to a very early period, that of Primitive Irish. This is an argument, not a proof.

Yet the Auraicept na n-Éces gives gorse (aiten) as the equivalent. The glossator seems no longer to have known the old meaning of onn and to have chosen another plant. McManus considers this identification mistaken. It shows, better than any long argument, that the “trees of ogham” are medieval glosses of uneven value, not an ancient code.

The associated tree or plant

Common gorse (Ulex europaeus) is a thorny shrub with bright yellow flowers that bloom almost all year round, with a peak in late winter and spring; its flowers give off a scent of coconut. It covers the coastal heaths of Ireland, Brittany and Wales. It burns easily and its spines wound: handle it with gloves.

The ash (Fraxinus excelsior) is a large tree with elastic, tough wood, used for tool handles, oars and, in Ireland, hurling sticks. It is now seriously affected by ash dieback, a fungal disease. Graves, in his 1948 calendar, did not make this letter a month.

The three portraits of the name (bríatharogam)

The three medieval lists evoke working wood and war, and suit the ash better than the gorse:

List	Old Irish expression	Approximate meaning
Morann mac Moín	congnaid ech	the one who wounds horses (the whip)
Mac ind Óc	féthem soíre	the smoothest of craftsmen's work
Cú Chulainn	lúth fían	strength (or equipment) of bands of warriors

These expressions are hard to translate: some may be corrupt, and the proposed translations are approximate. They are not reading instructions, only medieval images.

Modern divinatory reading

Modern readings most often connect Onn with gorse and make it the letter of tenacity, abundance, gathering and renewed energy: the shrub flowers in every season, it pricks but lights up the heaths. Others, closer to the old name, speak of an instrument, a well-made tool, a push to reach a goal.

Be aware that commercial ogham games do not agree on this point. Whichever reading you adopt, present it as a personal choice, not as a transmitted truth.

These meanings are modern: they come from ogham games and books published from the late twentieth century onward, and their authors do not always agree. Nothing proves that ogham was used for divination in ancient Ireland.

A reflective exercise

Think about what you are gathering at the moment: ideas, resources, people. Note what would prick those who come too close, and what gives light. Draw Onn and ask yourself which well-made tool you are missing. The exercise is about taking stock, not forecasting.