Zayin (also spelled zain or zayn or simply zay) is the seventh letter of the Semitic abjads, including Phoenician Zayin Phoenician zayin.svg, Hebrew 'Zayin ז, Aramaic Zain Zayin.svg, Syriac Zayn ܙ, and Arabic Zayn ز. It represents the sound [z].
The Phoenician letter gave rise to the Greek zeta (Ζ), Etruscan z 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 slang, zayin (זין) means "penis" and lezayen (לזין) is a vulgar term which generally means to perform sexual intercourse (similar to "fuck"), although the older meaning survives in maavak mezuyan ("armed struggle") (מאבק מזוין), kohot mezuyanim ("armed forces") (כוחות מזוינים), and beton mezuyan (בטון מזוין) ("armed, i.e., reinforced concrete"). The Proto-Sinaitic glyph may have been called ziqq, based on a hieroglyph depicting a "manacle".