Most European languages inflect at the end of words. Irish does something unusual: it changes the beginning. The initial consonant of a word shifts depending on what comes before it, and those shifts carry grammatical meaning rather than being merely phonetic.
Lenition softens
Lenition — séimhiú — is written by inserting an h after the first consonant.
| Base | Lenited | Sound shift |
|---|---|---|
| bád (boat) | bhád | b → v/w |
| cat (cat) | chat | c → kh |
| madra (dog) | mhadra | m → v/w |
| fear (man) | fhear | f → silent |
| teach (house) | theach | t → h |
| solas (light) | sholas | s → h |
Common triggers include the possessives mo (my) and do (your), the past-tense particle, the vocative particle a, and a feminine noun following the article.
| Irish | English | Trigger |
|---|---|---|
| mo chat | my cat | mo lenites |
| do bhád | your boat | do lenites |
| a Sheán! | Seán! (calling him) | vocative a |
| an bhean | the woman | feminine noun after an |
Eclipsis replaces
Eclipsis — urú — prefixes a consonant that takes over the pronunciation. The original letter stays in the spelling but goes silent.
| Base | Eclipsed | Pronounced |
|---|---|---|
| bád | mbád | mád |
| cat | gcat | gat |
| doras (door) | ndoras | noras |
| fuinneog (window) | bhfuinneog | vinneog |
| teach | dteach | dyach |
| páirc (field) | bpáirc | báirc |
Triggers include ár (our), bhur (your plural), a meaning their, the numbers seven to ten, and several prepositions combined with the article.
The mutation does the disambiguating. A chat is his cat, a cat is her cat, and a gcat is their cat. The word a is identical in all three; only the mutation on the following noun distinguishes the meaning. This is grammar carried entirely on the front of a word.
The verb comes first
Irish word order is verb-subject-object, which is rare worldwide and the main European example of the pattern.
| Irish | Literally | English |
|---|---|---|
| Tá mé go maith. | Am I good | I am well. |
| Itheann sé arán. | Eats he bread | He eats bread. |
| Chonaic mé an cat. | Saw I the cat | I saw the cat. |
Prepositions absorb pronouns
Irish fuses prepositions with pronouns into single words, and these are used constantly.
| Preposition | + mé | + tú | + sé |
|---|---|---|---|
| ag (at) | agam | agat | aige |
| ar (on) | orm | ort | air |
| le (with) | liom | leat | leis |
They matter because Irish expresses having, liking and many states through prepositions rather than verbs. There is no verb "to have": Tá cat agam is "is a cat at-me", meaning I have a cat.
How to approach it
Learn mutations with their triggers as phrases, never as an abstract table — mo chat, ár gcat, an bhean — so the trigger and the change arrive together. And for dictionary work, practise reversing them: strip the h for lenition, remove the prefixed consonant for eclipsis, and look up what remains.
The system is fully regular. Once the triggers are known, mutations stop being obstacles and start being what they are — information sitting at the front of the word.
Look up Irish offline
Mutations change the spelling, so lookup means restoring the base form. The free English-Irish Dictionary works with no connection.
Open the dictionary appFrequently asked questions
What is lenition in Irish?
A softening of the initial consonant, marked in modern spelling by adding an h — bád becomes bhád, cat becomes chat. It is triggered by particular words and grammatical contexts, including the possessive mo and do, the past tense particle, and feminine nouns after the article.
What is the difference between lenition and eclipsis?
Lenition softens the initial consonant and is written with an added h. Eclipsis replaces its sound entirely, written by prefixing another consonant — bád becomes mbád, cat becomes gcat. Different triggers cause each, and both are fully systematic.
Is Irish word order really verb-first?
Yes. Irish is verb-subject-object, so the verb opens the sentence — Tá mé go maith is literally Am I good. Only a small minority of the world's languages do this, and Celtic languages are the main European example.