Ypsilon

Ypsilon is the German name for the Latin letter Y and is also the name used for the Greek letter upsilon (Υ υ). In German-speaking contexts the letter Y is commonly referred to as "Ypsilon," a usage that extends into typography, education, and signage when spelling out the alphabet. The term helps distinguish the letter Y from other characters in written material.

The Greek upsilon is the 20th letter of the Greek alphabet. It traces back to the Phoenician waw and historically represented a vowel close to u or y; in Classical Greek it functioned as a long vowel, while in Modern Greek the letter denotes the close front unrounded vowel /i/. The uppercase form is Υ and the lowercase form is υ.

In modern usage, Ypsilon appears in science and mathematics as a conventional symbol for the letter Y: it can denote a variable, the Y-coordinate or Y-axis in graphs, or other quantities labeled with Y, just as other alphabetic symbols are used in formulas and notation. In German-language texts, the word Ypsilon is used to refer to the character itself rather than to its phonetic value.

Overall, Ypsilon links linguistic naming conventions for the letter Y in German with the historical and typographic history of the Greek letter upsilon, and it remains a standard designation in written language and technical notation.