Irish words can look intimidating to the Irish learner. But in many cases, the "extra" letters you see in a word actually provide helpful information about the role a word plays in a sentence, or provide helpful reminders that you need to produce a sound not found in English.

Broad and SlenderEdit

Each consonant letter in Irish can represent two different consonant sounds, called broad and slender. Although this phenomenon is common to most languages (viz English "cool", "calm" and "collected"), where the pronunciation of the consonant is determined by the preceding vowel, the Gaelic orthography is unique in mixing broad consonants with slender vowels and vice versa. In most languages, the preceding vowel decides whether a consonant is broad or narrow:

  • A consonant preceded by the vowels a, o, or u is a broad consonant.
  • A consonant preceded by i or e is described as slender.

In Irish, the convention has been developed to show on either side of a consonant, in cases of doubt, vowels which agree with each other so it is clear whether the consonant is broad or slender. One of these vowels (at least) will not be pronounced as a vowel, but merely shapes the following or preceding consonant.

In practice, this means that when a novice sees a word like "Lian", it's clear that the L is a slender consonant and the n a broad consonant, but you can't tell whether the vowel sound is an A and the letter I has been added just to show that the L is slender, or the vowel sound is an I and the A has been added to show that the N is broad. You must ask a native speaker, or use a dictionary showing IPA transcriptions.

Caol le caol agus leathan le leathanEdit

The golden rule for spelling in Irish, caol le caol agus leathan le leathan means slender with slender and broad with broad. The rule says that the vowels on either side of a consonant (or group of consonants) should agree; they should both be broad or both be slender. The rule is primarily used when you add an ending to a word (e.g., when conjugating a verb). To satisfy the rule you may need to add a vowel between the word and its ending. Note that there are a few common words (such as ansin and anseo) that do not satisfy this rule. However, the diphthong "ae" is considered broad, making words such as "Gaeltacht" and "aerfort" perfectly acceptable.


Even without knowing a single word of Irish, you can apply the rule to catch many spelling mistakes! Let's try a few examples:

Focus on the consonant in the center, l, and look at the vowels immediately before and after. The vowel before, o, is broad, and so is the vowel after, ú. This word follows the rule, so there aren't any obvious spelling mistakes here. (In fact, it is spelled correctly.)
Focus on the consonant group in the center, cf, and look at the vowels immediately before and after. The vowel before, a is broad, but the vowel after, i is slender. This looks like a mistake! (In fact, the correct spelling is glacfaidh).
The flanking vowels, o and a are both broad, so this word follows the rule.
The flanking vowels, i and e are both slender, so this word follows the rule.
Uh oh! The vowel before, i, is slender, but the vowel after, a is broad. (In fact, the correct spelling is dóimid).