Upsilon

Upsilon (ˈʌpsɪˌlɒn,ˈ(j)uːp-,-lən, UKalso(j)uːpˈsaɪlən,ʊp-,-lɒn; uppercase Υ, lowercase υ; ýpsilon ˈipsilon) or ypsilon Ip- is the twentieth letter of the Greek alphabet. In the system of Greek numerals, Υʹ has a value of 400. It is derived from the Phoenician waw . The name of the letter was originally just "υ" (y; also called hy, hence "hyoid", meaning "shaped like the letter υ"), but the name changed to "υ ψιλόν" u psilon 'simple u' to distinguish it from οι, which had come to have the same [y] pronunciation. In early Attic Greek (6th century BCE), it was pronounced u (a close back rounded vowel like the English "long o͞o"). In Classical Greek, it was pronounced y (a close front rounded vowel), at least until 1030. In Modern Greek, it is pronounced i; in the digraphs and , as [f] or [v]; and in the digraph as [u]. In ancient Greek, it occurred in both long and short versions, but Modern Greek does not have a length distinction. As an initial letter in Classical Greek, it always carried the rough breathing (equivalent to h) as reflected in the many Greek-derived English words, such as those that begin with hyper- and hypo-. This rough breathing was derived from an older pronunciation that used a sibilant instead; this sibilant was not lost in Latin, giving rise to such cognates as super- (for hyper-) and sub- (for hypo-). Upsilon participated as the second element in falling diphthongs, which have subsequently developed in various ways. The usage of Y in Latin dates back to the first century BC. It was used to transcribe loanwords from Greek, so it was not a native sound of Latin and was usually pronounced /u/ or /i/. The latter pronunciation was the most common in the Classical period and was used mostly by uneducated people. The Roman Emperor Claudius proposed introducing a new letter into the Latin alphabet to transcribe the so-called sonus medius (a short vowel before labial consonants), but in inscriptions, the new letter was sometimes used for Greek upsilon instead.