Eclipsis
Complete guide to Irish eclipsis (An tUrú): learn the 7 consonant mutations (b→mb, c→gc, d→nd, f→bhf, g→ng, p→bp, t→dt), vowels (n-), and grammatical triggers.
Eclipsis, known in Irish as urú, is one of the two most common initial consonant mutations. It changes the sound at the beginning of a word, typically by “voicing” a voiceless consonant (like p becoming b) or “nasalising” a voiced one (like b becoming m). This change is triggered by certain preceding words, such as prepositions, numbers, and possessive pronouns.
The Eclipsis Changes
Eclipsis affects seven consonants. In writing, the new sound is represented by adding a letter before the original initial consonant. The original letter is not pronounced.
b becomes mb
Rule b → mb
c becomes gc
Rule c → gc
d becomes nd
Rule d → nd
f becomes bhf
Rule f → bhf
g becomes ng
Rule g → ng
p becomes bp
Rule p → bp
t becomes dt
Rule t → dt
The table below summarises these changes and their approximate pronunciation for both broad and slender consonants.
| Initial Sound | Eclipsed Form | Pronunciation (Broad) | Pronunciation (Slender) |
|---|---|---|---|
b | mb | [m] | [mʲ] |
c | gc | [g] | [gʲ] |
d | nd | [n] | [nʲ] |
f | bhf | [v] or [w] | [vʲ] |
g | ng | [ŋ] (as in “sing”) | [ŋʲ] |
p | bp | [b] | [bʲ] |
t | dt | [d] | [dʲ] |
Before a vowel, some of the same grammatical triggers cause an n- to be prefixed to the word. This is known as n-prefixing.
How Eclipsis is Written
In written Irish, the eclipsing letter is added before the original letter, which is then silenced in pronunciation.
- ár dteach (our house) is pronounced as if it were written ár dteach.
When a word that is eclipsed needs to be capitalised, such as at the start of a sentence or in a title, the eclipsing letter remains lowercase while the original initial letter is capitalised.
- i gConnachta - in Connacht
- i nGaeilge - in Irish
- i mBéarla - in English
When to Use Eclipsis
Eclipsis is triggered by specific grammatical contexts.
After Certain Prepositions with the Article
Eclipsis occurs after the prepositions ar, as, faoi, le, ó, roimh, thar, trí, and um when they are followed by the singular definite article an.
- ar an mbord - on the table
- leis an gcailín - with the girl (
le+an=leis) - tríd an bhfuinneog - through the window (
trí+an=tríd)
After the Preposition sa
The form sa (a contraction of i + an, meaning “in the”) causes eclipsis on the following noun.
- sa bhfarraige - in the sea
After the Preposition i
The preposition i (in) causes eclipsis when it is not followed by the definite article.
- i dteach - in a house
- i bpáirc - in a park
After the Genitive Plural Article na
Eclipsis is used on nouns following na when it is the article for the genitive plural (meaning “of the”).
- hataí na bhfear - the hats of the men
- dath na gcarranna - the colour of the cars
After Plural Possessive Adjectives
The plural possessive adjectives ár (our), bhur (your, plural), and a (their) all trigger eclipsis.
- ár dtír - our country
- bhur mbord - your table
- a gcarr - their car
After Numbers 7-10
The cardinal numbers from seven to ten cause eclipsis on the following noun. This also applies to compound numbers ending in 7-10, like 17 or 27.
- seacht gcat - seven cats
- ocht bpeann - eight pens
- naoi dtiachóg - nine kites
- deich mbád - ten boats
After Certain Verbal Particles and Conjunctions
Eclipsis is used on a verb following these common particles and conjunctions: an (question particle), go (that), nach (that…not), mura (if…not), dá (if), and sula (before).
- An bhfuil tú ann? - Are you there?
- Dúirt sé go dtiocfadh sé. - He said that he would come.
- Mura gcreideann tú mé… - If you don’t believe me…
After Other Particles
Eclipsis also occurs in a few other specific situations:
- After the interrogative
cá(where): Cá bhfuil sé? - Where is he? - After the indirect relative particle
a: an fear a bhfuil a mhac tinn - the man whose son is sick - After the generalising relative pronoun
a(all that): sin a bhfuil uaim - that is all that I want
After the Prefix éa-
The prefix éa-, meaning “un-”, causes eclipsis. In modern spelling, the original eclipsed letter is usually omitted entirely.
éa-+cóir(just) →éagóir(injustice)éa-+trom(heavy) →éadrom(light, not heavy)
Archaic and Fossilised Forms
You may encounter eclipsis in older texts or fixed phrases where the rules were applied differently.
- In place names: Some place names preserve an older eclipsis that followed a neuter noun, e.g., Loch nEachach (Lough Neagh).
- On adjectives: It was once common to eclipse an adjective that followed an eclipsed noun in the genitive plural, e.g., scéal na mban mbocht (the story of the poor women). This is rare in modern Irish.
Historical note on older spellings
In older texts, you might see a different way of writing eclipsis where the eclipsed letter was doubled. For example, cc was used instead of gc for [g], and tt instead of dt for [d]. So, go bhfuil might have been written as go ffuil, and nach dtuigim as nach ttuigim. This convention is no longer used.