Zeta is the sixth letter of the Greek alphabet. In the system of Greek numerals, it has a value of 7. It was derived from the Phoenician letter zayin Zayin. Letters that arose from zeta include the Roman Z and Cyrillic З.
Unlike the other Greek letters, this letter did not take its name from the Phoenician letter from which it was derived; it was given a new name on the pattern of beta, eta and theta.
The word zeta is the ancestor of zed, the name of the Latin letter Z in British English. Swedish and many Romanic languages (such as Italian and Spanish), do not distinguish between the Greek and Roman forms of the letter; "zeta" is used to refer to the Roman letter Z as well as the Greek letter.