Tau gallicum

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Tau gallicum" – news · newspapers · books · scholar · JSTOR (November 2020) (Learn how and when to remove this message)

Tau gallicum, or D with short stroke overlay in Unicode, (majuscule: Ꟈ (), minuscule: ꟈ ()) is a letter that was used to write the Gaulish language.^[1] It is a D with the horizontal bar from the Greek letter Θ.^[1] It likely represented a /t͡s/ or /st/ sound,^[1] like the ts in cats or the st in stop. In modern times, it is used in the Cubeo and Daasanach languages to represent the sound [ð], in the Northern Embera language to represent the sound [ɗ], and in the Moro language.

This article contains IPA phonetic symbols. Without proper rendering support, you may see question marks, boxes, or other symbols instead of Unicode characters. For an introductory guide on IPA symbols, see Help:IPA.

The Latin phrase tau gallicum literally means "Gallic tau". 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.^[2] The second epigram contains the following text:

Corinthiorum amator iste uerborum,
iste iste rhetor, namque quatenus totus
Thucydides, tyrannus Atticae febris:
tau Gallicum, min et sphin ut male illisit,
ita omnia ista uerba miscuit fratri.

— Virgil, Catalepton II

It is not known, however, whether the sound described by Virgil is the same as that for which the term is currently used.

After using the Greek alphabet, the Gauls adopted the Latin alphabet to transcribe their language. However, to note a sound unknown to the second, they introduced the additional letter tau gallicum, said to have been inspired by the Greek letter Θ (theta). Its spelling is varies between ⟨Ꟈ⟩ and ⟨ꟉꟉ⟩.^[1]

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 the Gallic language with Latin cursive letters: snIeꟈꟈdic, aꟈꟈedillI.

The precise value of the sound transcribed by the Gallic tau is not known. It is supposed that it denotes an alveolar affricate /t͡s/, in free variation with [st] in initial position.

The letter is encoded into Unicode as U+A7C7 Ꟈ LATIN CAPITAL LETTER D WITH SHORT STROKE OVERLAY and U+A7C8 ꟈ LATIN SMALL LETTER D WITH SHORT STROKE OVERLAY respectively.