Ayin (Hebrew: עַיִן, Modern: ʿayin, Tiberian: ʿayin) is the sixteenth letter of the Modern Hebrew Alphabet. It is also the sixteenth letter of the Semitic abjads, including Phoenician, Aramaic, Syriac, Arabic (where it is known as ʿayn, عين), and others. In Arabic, it is the eighteenth letter of the alphabet. The shape of the letter can vary dramatically between languages and historical periods. In Hebrew, it is written as ע and represents a voiced pharyngeal fricative (IPA: ʕ), a sound similar to that of the English "ow" in "cow" but produced further back in the throat. In Arabic, the letter is written as ع and represents the same sound. The letter ayin is derived from a Proto-Sinaitic glyph that may have depicted an eye, based on the Egyptian hieroglyph for an eye. The Greek letter Omicron (Ο) and the Latin letter O are believed to be derived from this Semitic letter. In Hebrew, the letter ayin has a numerical value of 70 in gematria.