The Irish Language Grimoire – Alphabet

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The alphabet is the foundation. Before you can read an Irish word, conjugate a verb, translate a sentence, or recognise a name, you have to know the letters and how to say them. This page is the dedicated reference for that foundational layer of the language.

The Irish alphabet is laid out here in five sections. Click any letter on the grid below to see every Grimoire entry beginning with that letter, the Ogham tree-name associated with it, and a pronunciation note specific to that letter.

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The eighteen letters

The traditional Irish alphabet has eighteen letters, in this order:

a b c d e f g h i l m n o p r s t u

Each letter has its own card below. Tap any card to open that letter’s full Grimoire page, where every word beginning with that letter is grouped by theme. The Ogham tree-name (ailm, beith, coll…) is the medieval Irish name for each letter, drawn from the alphabet of carved tree-letters used on inscribed stones.

What’s not in the traditional alphabet: j, k, q, v, w, x, y, z. These letters appear only in loanwords and modern coinages — vóta (vote), zú (zoo), jab (job). For everything native to Irish, the eighteen letters above are the whole set.

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The fada

The síneadh fada (“long mark”) is the diagonal stroke over a vowel: á é í ó ú. It is not a stress mark. It is not decorative. It changes the vowel from short to long, and the long version is often a different word entirely.

cat means cat. cát means cake. The fada is the only thing distinguishing them on the page.

A fuller fada lesson with all five vowel pairs and minimal-pair examples is in the editorial queue.

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Broad and slender consonants

Irish consonants come in two flavours: broad (leathan) and slender (caol). Which flavour a consonant has depends on which vowel sits next to it. The rule has its own name: caol le caol agus leathan le leathan — slender with slender, broad with broad.

• Broad vowels — a, o, u (and their long forms á, ó, ú)
• Slender vowels — e, i (and their long forms é, í)

A consonant standing next to a broad vowel is pronounced one way; the same consonant next to a slender vowel is pronounced another way entirely. bád (boat, broad b) sounds like “bawd”; béal (mouth, slender b) sounds like “bay-ul.” Same letter, two sounds.

This is the single biggest concept that takes English speakers by surprise. It also explains why every Irish vowel cluster is doing exactly the work it appears to be doing — the seemingly extra vowels are flagging the consonant’s flavour.

A side-by-side comparator widget for broad/slender consonants is in the editorial queue.

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Lenition (séimhiú)

Lenition is a softening. In modern spelling, an h is added after a consonant to mark that the consonant has been softened. In older or handwritten Irish, a dot above the letter does the same job.

The trigger for lenition is grammatical, not phonetic. Possessive pronouns trigger it (mo + cat becomes mo chat, “my cat”). Certain prepositions trigger it. The past tense triggers it. The vocative case triggers it. A learner meets lenition the moment they meet possession.

A full lenition lesson with every trigger and worked examples is in the editorial queue.

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Ogham, the tree alphabet

Long before Irish was written in the Latin alphabet, it was carved into stone in Ogham (ogham, pronounced “OH-um”): a script of straight strokes cut along the edge of a stone, dated to roughly the 4th to 9th centuries. About 400 surviving Ogham stones are scattered across Ireland and the Irish-settled coasts of Britain.

Many Ogham letters carry tree-names — beith (birch), coll (hazel), dair (oak), fearn (alder), sail (willow). The popular framing of Ogham as a “Celtic Tree Alphabet,” however, is a 20th-century reinterpretation, not the original system. The scholarly consensus, established by Damian McManus in A Guide to Ogam (1991), is that only about a third of the original 20 letter-names were actually tree-names; the rest were given arboreal glosses in the medieval Auraicept na n-Éces tradition. The medieval Bríatharogaim (“word-omens”) give a poetic phrase for each letter — short kennings that capture each letter’s meaning, and the kennings only sometimes invoke trees.

Two phases of Ogham — orthodox and scholastic

Ogham survives across two distinct phases, and any claim about Ogham depends on which phase is being discussed:

• Orthodox phase (roughly the 4th to 6th centuries) — Ogham carved along the edges of stone monuments, in Primitive Irish. About 400 of these stones survive in Ireland and along the Irish-settled coasts of Britain (Wales, Cornwall, the Isle of Man, and Scotland). Each inscription typically names a person, often a chieftain, often with their lineage.
• Scholastic phase (roughly the 6th to 9th centuries onward) — Ogham written on a stemline (a horizontal central line drawn on a manuscript page or carved on a stone face), in Old Irish. Almost everything we know about Ogham theory — the letter-names, the kennings, the forfeda, the four aicme classification — comes from this phase, especially the medieval treatise Auraicept na n-Éces (“The Scholars’ Primer”).

A claim about what was carved on a 5th-century stone is not the same kind of claim as a passage from a 14th-century manuscript treatise. The two phases are continuous in tradition but separated by centuries of development in the Irish language and in scribal practice.

The eighteen letters in Ogham

The traditional Irish alphabet rendered in Ogham, with its modern Latin equivalent and Irish letter-name. The brackets at each end (᚛ ᚜) are the Ogham feather marks that begin and end an inscription.

Ogham reads bottom to top on a vertical edge of stone (the original orientation), or left to right when laid horizontally on a page. The strokes are grouped into four aicme (families) of five letters each, plus a small set of later additions called forfeda. The “letter” is really the count and side of the strokes relative to the central line.

Sample inscriptions

How a name or word looks rendered in Ogham:

How Ogham works — the four aicme (families)

Ogham is built around a clean grammar: a single central line (the droim, “ridge” — historically the edge of a stone) with strokes cut on, across, or beside it. The strokes come in four aicme (families) of five letters each. Within each aicme, the letters are distinguished only by how many strokes are cut: one through five. That’s it. Twenty letters, four orientations, five stroke-counts.

This is why Ogham was practical to carve into stone with a chisel — every letter is a small set of straight cuts. No curves, no diacritics, no ambiguous letterforms. A literate carver could work fast. A literate reader could decode an inscription by counting strokes.

Three letters in this table are marked with a dagger (†): Q (queirt, “apple”), NG (ngeadal), and Z (straif, “blackthorn”). These were part of the original 20-letter Ogham but are not in the modern 18-letter Irish alphabet. Their sounds either changed historically (Q became C in most words) or merged into other spellings (NG is now written ng with two letters; Z is essentially absent in native Irish vocabulary).

Reading direction

Real Ogham inscriptions on stone read bottom to top along the vertical edge of the stone, then continue across the top and down the other side if the inscription is long. When laid flat on a page (as on this site), Ogham reads left to right, the way Latin text does.

The opening bracket (᚛, U+169B) marks where an inscription begins. The closing bracket (᚜, U+169C) marks where it ends. Most surviving stone inscriptions have only the opening bracket; the closing one is rarer.

The forfeda — five later additions

The forfeda (“supplementary letters”) are five extra Ogham characters added in the medieval period — roughly the 6th to 9th centuries — to handle sounds the original 20 letters didn’t cover well. They appear on later inscriptions and in manuscript treatises like In Lebor Ogaim (“The Book of Ogams”). The values these letters represented varied by tradition; most are unstable across sources.

So the full Ogham repertoire is 20 original letters + 5 forfeda = 25 characters, all encoded in the Unicode block U+1680 through U+169F. Modern Irish uses 18 of these (the original 20 minus Q, NG, Z, plus the modern PEITH ᚚ for p).

Worked example — reading a stroke-count

Take the inscription ᚛ᚇᚐᚔᚏ᚜. Read left to right:

• ᚇ — H-aicme, 2 strokes left of the line → D (dair, oak)
• ᚐ — A-aicme, 1 stroke across the line → A (ailm, pine)
• ᚔ — A-aicme, 5 strokes across the line → I (iodhadh, yew)
• ᚏ — M-aicme, 5 strokes angled across the line → R (ruis, elder)

So the inscription reads DAIR — “oak”. This is exactly how a learner-grade Ogham primer parses an inscription: identify the aicme by orientation, count the strokes, look up the letter.

If you see boxes (□) instead of Ogham strokes, your device is missing the Ogham font. The script is part of the Unicode standard (block U+1680–U+169F) and renders natively on Windows 10+, macOS 12+, and recent Linux distributions. Older systems may need the free “Beith-Luis-Nion” Ogham font installed manually.

The link between the modern Irish alphabet and Ogham is direct. Each card at the top of this page shows the modern letter, its Irish letter-name, and its Ogham character side by side so the connection stays visible.

Real Ogham stones — a curated gallery

About 400 Ogham stones survive across Ireland and the Irish-settled coasts of Britain. Below are ten representative inscriptions, drawn from the Macalister Corpus Inscriptionum Insularum Celticarum (CIIC, 1945) and the modern scholarly editions on Ogham in 3D (DIAS) and the OG(H)AM Project (University of Glasgow). Each card shows the inscription in Ogham, a Roman transliteration, a translation, the historical period, and a brief scholarly note. Click the CIIC chip to open the stone’s entry in the digital corpus.

The selection covers six Irish stones across Munster, Ulster, and Leinster, plus one each from Wales, Cornwall, the Isle of Man, and Scotland. Eight are orthodox-phase memorial stones (4th–6th c., carved along stone edges in Primitive Irish); one (Arraglen) marks the Christian transition with a chi-rho monogram; and one (Inchmarnock) is a scholastic-phase alphabet practice slate from an 8th-century Scottish monastic school — a literal pupil’s exercise.

Further reading on Ogham

For readers who want to go deeper than this primer:

• Damian McManus, A Guide to Ogam (Maynooth Monographs 4, An Sagart, 1991) — the modern scholarly standard. McManus corrected the older Macalister readings and is the source for almost every claim on this page about letter-names, kennings, and inscription dating. Free scan available at the Internet Archive.
• David Stifter, Ogam: Language, Writing, Epigraphy (Anejo de AELAW 10, Prensas de la Universidad de Zaragoza, 2022) — the newest scholarly synthesis, integrating the discoveries of the Ogham 3D and OG(H)AM Project digitisation programmes since McManus.
• Ogham in 3D (Dublin Institute for Advanced Studies) — laser-scanned 3D models of Ogham stones, browsable by CIIC number, with transcriptions and translations.
• OG(H)AM Project (University of Glasgow) — open-access database covering Ogham inscriptions across Britain and Ireland, including the cross-channel inscriptions on the Isle of Man and in Wales.
• Auraicept na n-Éces on CELT (University College Cork) — the medieval Irish primer on Ogham theory, edited by George Calder (1917), full text searchable.
• Ogham Academy — community-grade resource by Lora O’Brien, with a helpful trustworthy-sources reading list for non-specialists. Useful for anyone wanting to distinguish primary scholarship from speculative tradition.

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