Ceirt is a letter of the Ogham

Ogham

Ogham is an Early Medieval alphabet used primarily to write the Old Irish language, and occasionally the Brythonic language. Ogham is sometimes called the "Celtic Tree Alphabet", based on a High Medieval Bríatharogam tradition ascribing names of trees to the individual letters.There are roughly...

 alphabet, transcribed as Q. It expresses the Primitive Irish labiovelar phoneme. The 14th century Auraicept na n-Éces

Auraicept na n-Éces

Auraicept na n-Éces is claimed as a 7th century work of Irish grammarians, written by a scholar named Longarad....

glosses the name as aball, meaning "apple tree". Its phonetic value is [kʷ].

The Bríatharogam

Bríatharogam

In Early Irish literature a Bríatharogam is a two word kenning which explains the meanings of the names of the letters of the Ogham alphabet. Three variant lists of bríatharogaim or 'word-oghams' have been preserved, dating to the Old Irish period...

(kennings) for the letter are:

• Morainn mac Moín: Clithar baiscill ‘the shelter of a lunatic’
• Maic ind Óc: Bríg anduini ‘substance of an insignificant person’
• Con Culainn: Dígu fethail ‘dregs of clothing’

McManus (1991:37) compares it to Welsh pert ‘bush’ , Latin quercus ‘oak’ (PIE

Pie

A pie is a baked dish which is usually made of a pastry dough casing that covers or completely contains a filling of various sweet or savoury ingredients....

 *perkwos). The name was confused with Old Irish ceirt ‘rag’, reflected in the kennings.

In the framework of a runic

Elder Futhark

The Elder Futhark is the oldest form of the runic alphabet, used by Germanic tribes for Northwest Germanic and Migration period Germanic dialects of the 2nd to 8th centuries for inscriptions on artifacts such as jewellery, amulets, tools, weapons and runestones...

 origin of the Ogham, the name has also been compared to the name of the Anglo Saxon

Old English language

Old English or Anglo-Saxon is an early form of the English language that was spoken and written by the Anglo-Saxons and their descendants in parts of what are now England and southeastern Scotland between at least the mid-5th century and the mid-12th century...

 Futhorc p-rune, Peorð

Peorð

' is the rune denoting the sound p in the Elder Futhark runic alphabet, in the Anglo-Saxon rune poem named peorð. It does not appear in the Younger Futhark. In the poem, it is glossed with the enigmatic:...

: This name is itself unclear, but most often identified as ‘pear

Pear

The pear is any of several tree species of genus Pyrus and also the name of the pomaceous fruit of these trees. Several species of pear are valued by humans for their edible fruit, but the fruit of other species is small, hard, and astringent....

’, a meaning not unrelated to ‘apple’. Interestingly, the p letter of the Gothic alphabet

Gothic alphabet

The Gothic alphabet is an alphabet for writing the Gothic language, created in the 4th century by Ulfilas for the purpose of translating the Christian Bible....

 has a cognate name, pairþra, alongside the clearly related qairþra, the name for the Gothic labiovelar. Since an influence of Ogham letter names on Gothic letter names is eminently unlikely, it seems most probable that the Proto-Germanic p rune had a meaning of ‘pear tree’ (*pera-trewô?), continued in the Anglo-Saxon peorð rune (with the meaning of the name forgotten), and was introduced into 4th century Ireland as the name of a rune named after a pear or apple tree. As p was nonexistent as a phoneme in Primitive Irish, the p and q runes would have been considered equivalent.