Y, 25th letter of the alphabet. It was a Latin importation of the eastern Greek upsilon (see U), which was pronounced like ü; the Romans used it for Greek words. In English y mainly represents the semivowel occurring in words such as yet; the same semivowel is the second member of the diphthongs ā, ē, Ī, and oi. The modern ignorant use of y in ye for the (as in "Ye Olde Shoppe") is based on a misreading of an old sign for th. In chemistry Y is the symbol for the element yttrium.