Ailm is the Irish name of the sixteenth letter of the Ogham alphabet, ᚐ. Its phonetic value is [a]. The original meaning of the name cannot be established with certainty. The Bríatharogam kennings all refer to the sound [a] and not to the meaning of the letter name, either as the sound of a "groan", or to the Irish vocative particle, á. Thurneysen suggests that Ailm, Beithe was influenced by Alpha, Beta. However, beithe is an Irish word, and there is no reason to consider ailm a sole, loaned letter name among the original feda; Thurneysen did not suggest this letter name involved such a borrowing. The word is attested once outside of the Ogham grammatical texts, in the poem "King Henry and the Hermit",