Zayin (also spelled zain or zayn or simply zay) is the seventh letter of many Semitic abjads, including Phoenician 𐤆, Aramaic, Hebrew ז, Syriac ܙ and Perso-Arabic alphabet ز (see below). It represents the sound [z].

The Phoenician letter gave rise to the Greek zeta (Ζ), Etruscan z , Latin Z, and Cyrillic Ze З.

The Phoenician letter appears to be named after a sword or other weapon. In Biblical Hebrew, zayin (זין) means "sword", and the verb lezayen (לזיין) means "to arm". In modern Hebrew, zayin (זין) means "penis" and lezayen (לזין) is a vulgar term which generally means to perform sexual intercourse (similar to "fuck"),^[1] although the older meaning survives inmaavak mezuyan ("armed struggle") (מאבק מזוין) and beton mezuyan (בטון מזוין) ("armed, i.e., reinforced concrete"). The Proto-Sinaitic glyph may have been called ziqq, based on ahieroglyph depicting a "manacle".^[2]

In modern Hebrew the frequency of the usage of zayin, out of all the letters, is 0.88%.

Hebrew spelling: זַיִן

In modern Hebrew, the combination ז׳ (zayin followed by a geresh) is used in loanwords and foreign names to denote [ʒ] as in vision.

In gematria, zayin represents the number seven,^[3] and when used at the beginning of Hebrew years it means 7000 (i.e. זתשנד in numberswould be the future date 7754).

Zayin is also one of the seven letters which receive a special crown (called a tagin) when written in a Sefer Torah, besides ʻayin, gimel,teth, nun, shin, and tzadi.

It is one of several Hebrew letters that have an additional meaning as a noun. The others are: bet [ב, the 2nd letter], whose name is a grammatical form of the word for 'house' (בית); vav [ו, the 6th letter], whose name means 'hook' (וו); kaf [כ, the 11th], whose name means 'palm [of the hand]' (כף); ʻayin [ע, the 16th], whose name means 'eye' (עין); pe [פ, the 17th], whose name means 'mouth' (פה); qof [ק, the 19th], whose name means 'monkey' (קוף); shin [ש, the 21st], whose name means 'tooth' (שין); tav [ת, the 22nd], whose name means 'mark' (תו), and several other Hebrew letters, whose names are ancient Hebrew forms of nouns still used, with a slight change of form or pronunciation, as nouns in modern Hebrew.^[4]

Zain is a consonant with the /z/ sound which is a voiced alveolar fricative.

The letter is named zayn/zāy/zāʾ. It has two forms, depending on its position in the word:

The similarity to rāʼ  ر  is likely a function of the original Syriac forms converging to a single symbol, requiring that one of them be distinguished as a dot; a similar process occurred to jīm and ḥāʼ.

The same letter has another name – ze – in a number of languages, such as Persian.

It also has a modified version: ژ Persian pronunciation: [ʒe], which is used in Persian, Pashto,Kurdish, Urdu and Uyghur (see K̡ona Yezik̡).