y

Y is the twenty-fifth letter of the modern Latin alphabet. It is used in many languages that use the Latin script, with both uppercase and lowercase forms.

The letter Y was added to the Latin alphabet in antiquity to represent the Greek upsilon in words borrowed from Greek. In Latin texts it was often labeled y graeca to distinguish it from other letters, and its presence helped accommodate sounds found in Greek loanwords. In modern languages, the name and precise usage of Y vary, with German calling it Ypsilon and other languages sometimes referencing its Greek origin.

In phonology, Y has a dual role in many languages. It can function as a consonant, most commonly the palatal approximant pronounced like the English “y” in yes. It can also act as a vowel, taking on various sounds depending on the language and the word, such as representing a long or short vowel in English endings or serving as a syllable nucleus in other languages.

Common uses in writing and science include its role as a letter in spelling and typography, its function as a variable in mathematics and physics, and its designation as the dependent variable or the y-axis on graphs. In biology, Y denotes the Y chromosome, which plays a key role in male inheritance. In chemistry, the symbol Y represents the element Yttrium, with atomic number 39.

The letter Y also appears in various abbreviations, brands, and cultural references, and the word why is often used in puns and wordplay connected to the letter itself.