Y is the twenty-fifth letter of the Latin alphabet.

See V. In Ancient Greek Υψιλον (Ypsilon) was pronounced IPA [u], later on [y], now [i] (see English myth [of Greek origin] and gift [of Old English origin] which both have ). The Romans borrowed Y directly from the Greek, because they felt that V no longer adequately represented Greek [y]. The English name of the letter, pronounced [waɪ], is of unknown origin.

In Spanish, Y is called i griega, in Catalan i grega and in French and Dutch i grec (all mean "Greek i"); in most other European languages the Greek name is still used. The letter Y was originally established as a vowel. In the standard English language, the letter Y is traditionally regarded as a consonant, but as a survey of almost any English text, including this one, will show, Y more commonly functions as a vowel.

The letter y was used by Caxton and other printers in mediaeval England to represent the thorn (Þ, þ), resulting in the old-fashioned spelling ye for the word the.

Originally, Y was a vowel letter in Greek, representing [u] and later on, front rounded [y], becoming [i] in Modern Greek. It has the sound value [y] in German, in Finnish and the Scandinavian languages, where it can never be a consonant. In contrast, in the Latin transcription of Nenets (Nyenec) the letter "y" palatalizes the preceding consonant. The letter Y nicely shows how letters change their function. In Afrikaans, Y denotes the diphthong [EI], probably as a result of mixing lower case i and y or may derive from the IJ ligature. In Dutch, Y appears only in loanwords and names and is usually pronounced [i]. It is often left out of the Dutch alphabet and replaced with the "letter IJ". Italian, too, has Y only in very few loanwords.

In Castilian language, Y was used as a word-initial form of I that was more visible. German has used J in a similar way. Hence el Yugo y las Flechas was a symbol sharing the initials of Isabella I of Castile (Ysabel) and Ferdinand II of Aragon. This spelling was reformed by the Royal Spanish Academy and currently is only found in proper names spelt archaicly, such as Ybarra or CYII , the symbol of the Canal de Isabel II . X is also still used in Spanish with a different sound in some archaisms. In Spanish names, an y (meaning "and") can separate the father surname from the mother surname as in "Santiago Ramón y Cajal". Catalan names use i for this.

Yankee represents the letter Y in the NATO phonetic alphabet. In the International Phonetic Alphabet, [y] corresponds to the close front rounded vowel, and [ʏ] corresponds to the near-close near-front rounded vowel.

Meanings for Y

• "The Y" is short for:
  • the YMCA, or sometimes, the YWCA.
  • Brigham Young University (BYU) or the large "Y" made of stones on the mountain overlooking BYU.
• In biochemistry, Y is the symbol for tyrosine.
• In chemistry, Y is the symbol for yttrium.
• In color models,
  • Y stands for the color yellow in the CMYK color model.
  • Y stands for luminance in many color models used for television broadcast, such as YIQ and YUV.
• In combinatory logic, Y is the name of a well known fixed point combinator.
• In comic books, Y: The Last Man is the title of a DC comics series by Brian K. Vaughan.
• In command line interpreters like 4DOS, y is a command to concatenate the output of two or more streams .
• In electrical engineering, Y is the symbol for admittance, the inverse of impedance.
• In film, Y is the name of a 1987 Swedish film; see Y (film) .
• In games, Y is the name of a modern board game, played on a triangle-shaped board; see Y (game)
• In geography,
  • Y is the name of a place in Alaska; see Y, Alaska.
  • Y is the name of a municipality in the Somme département of France; see Y, France.
• In mathematics, y is the usual symbol for the variable represented on the vertical axis (ordinate) in analytic geometry.
• In the Metric system,
  • Y, yotta is the SI prefix meaning 10²⁴.
  • y, yocto is the SI prefix meaning 10^-24.
• As the first letter of a postal code,
  • In Canada, Y stands for the Yukon.
• In sociology, Y refers to Generation Y.
• In statistics and analysis, y commonly denotes the dependent variable.
• In video games, Y is an abbreviation for Yoshi, a Nintendo character.
• In economics, Y is used to represent income.

See also