Upsilon


Upsilon or ypsilon is the 20th letter of the Greek alphabet. In the system of Greek numerals, label=none has a value of 400. It is derived from the Phoenician waw.
vessel, with a V-shaped upsilon

Etymology

The name of the letter was originally just "υ", but the name changed to "υ ψιλόν" u psilon 'simple u' to distinguish it from οι, which had come to have the same pronunciation.

Pronunciation

In early Attic Greek, it was pronounced . In Classical Greek, it was pronounced , at least until 1030. In Modern Greek, it is pronounced ; in the digraphs αυ and ευ, as or. 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 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- and sub-.
Upsilon participated as the second element in falling diphthongs, which have subsequently developed in various ways.

Correspondence with Latin Y

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 or. 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, but in inscriptions, the new letter was sometimes used for Greek upsilon instead.
Four letters of the Latin alphabet arose from it: V and Y and, much later, U and W. In the Cyrillic script, the letters U and izhitsa arose from it.
In some languages, the name upsilon is used to refer to the Latin letter Y as well as the Greek letter.

Usage

Upsilon is known as Pythagoras' letter, or the Samian letter, because Pythagoras used it as an emblem of the path of virtue or vice. As the Roman writer Persius wrote in Satire III:
Lactantius, an early Christian author, refers to this:

Character encodings

These characters are used only as mathematical symbols. Stylized Greek text should be encoded using the normal Greek letters, with markup and formatting to indicate text style.