Tau gallicum

The Latin phrase literally means "Gallic tau", referring to the nineteenth letter of the Greek alphabet. The only known mention of the letter is found in Catalepton, a set of epigrams attributed to Virgil and collected after his death in Appendix Vergiliana. The second epigram contains the following text: It is not known, however, whether the sound described by Virgil is the same as that for which the term is currently used. == Letter ==

After using the Greek alphabet, the Gauls transcribed their language using the Latin alphabet. However, to note a sound unknown to it, they introduced the additional letter tau gallicum, said to have been inspired by the Greek letter Θ (theta). Its spelling varies between and . The letter can be found in the initial of the name of the Celtic goddess Sirona, whose name is written as: Sirona, Ꟈirona or Thirona, highlighting the difficulty of noting the initial sound in the Latin alphabet. The letter is also present in the lead of Chamalières, a lead tablet discovered in 1971 in Chamalières and written in Gaulish with Latin cursive letters: snIeꟈꟈdic, aꟈꟈedillI. == Pronunciation ==

The precise value of the sound transcribed by the Gallic tau is not known. It is supposed that it denotes an alveolar affricate , in free variation with in initial position. ==Use on computers==

The letter is encoded into Unicode as and respectively. == References ==