Claudian letters

The Claudian letters were developed by the Roman emperor Claudius (reigned 41–54). He introduced three new letters to the Latin alphabet:

• Ↄ or ⵋ/X (antisigma) to replace BS and PS, much as X stood in for CS and GS. The shape of this letter is disputed, however, since no inscription bearing it has been found. Franz Bücheler identified it with the variant Roman numeral Ↄ, but 20th century philologists, working from copies of Priscian's books, believe it to instead resemble two linked Cs (Ↄ+Ϲ), which was a preexisting variant of Greek sigma, and easily mistaken for X by later writers. Revilo P. Oliver argued that Claudius would have based this letter upon the Arcadian variant of psi or . This letter should not be confused with the "open O" letter. (Ɔ)
• Ⅎ, a turned F or digamma (digamma inversum) to be used instead of the letter V when denoting the consonantal phoneme (w/β). Thus, it resembles the use of the letter V in modern Latin texts, where the vocalic use of the letter V is represented by its variant U which has been recognized as a different letter only later.
• Ⱶ, a half H. The value of this letter is unclear, but it may have represented the so-called sonus medius, a short vowel sound (likely /ɨ/ or /ʉ/) used before labial consonants in Latin words such as optumus and optimus. The letter was later used as a variant of y in inscriptions for short Greek upsilon (as in Olympicus). It may have disappeared because the sonus medius itself disappeared from spoken language.