Yodh

In both Biblical and Modern Hebrew, Yod represents a palatal approximant ([j]). As a mater lectionis, it represents the vowel [i]. At the end of words with a vowel or when it is marked with a sh'va nach, it represents the formation of a diphthong, such as /ei/, /ai/, or /oi/.

In gematria, Yod represents the number ten.

As a prefix, it designates the third person singular (or plural, with a Vav as a suffix) in the future tense.

As a suffix, it indicates first person singular possessive; av (father) becomes avi (my father).

"Yod" in Hebrew signifies iodine. Iodine is also called يود yod in Arabic.

Two Yods in a row designate the name of God Adonai and in pointed texts are written with the vowels of Adonai, which is done as well with the Tetragrammaton.

As Yod is the smallest letter, much kabbalistic and mystical significance is attached to it. According to the Gospel of Matthew, Jesus mentioned it during the Antithesis of the Law, when he says: "One jot or one tittle shall in no wise pass from the law, till all be fulfilled." Jot, or iota, refers to the letter Yod; it was often overlooked by scribes because of its size and position as a mater lectionis. In Modern Hebrew, the phrase "tip of the Yod" refers to a small and insignificant thing, and someone who "worries about the tip of a Yod" is someone who is picky and meticulous about small details.

Much kabbalistic and mystical significance is also attached to it because of its gematria value as ten, which is an important number in Judaism, and its place in the name of God.[4]

In Yiddish,[5] the letter yod is used for several orthographic purposes in native words:

• Alone, a single yod י may represent the vowel [i] or the consonant [j]. When adjacent to another vowel, or another yod, [i] may be distinguished from [j] by the addition of a dot below. Thus the word Yidish 'Yiddish' is spelled ייִדיש. The first yod represents [j]; the second yod represents [i] and is distinguished from the adjacent [j] by a dot; the third yod represents [i] as well, but no dot is necessary.
• The digraph יי, consisting of two yods, represents the diphthong [ej].
• A pair of yods with a horizontal line (pasekh) under them, ײַ, represents the diphthong [aj] in standard Yiddish.
• The digraph consisting of a vov followed by a yod, וי, represents the diphthong [oj].

In traditional as well as in YIVO orthography, Loanwords from Hebrew or Aramaic in Yiddish are spelled as they are in their language of origin. In Soviet orthography, they are written phonetically like other Yiddish words.

In the Persian alphabet, the letter is generally called ye following Persian-language custom. In its final form, the letter does not have dots (ی), much like the Arabic Alif maqṣūrah or, more to the point, much like the custom in Egypt, Sudan and sometimes Maghreb. On account of this difference, Perso-Arabic ye is located at a different Unicode code point than both of the standard Arabic letters. In computers, the Persian version of the letter automatically appears with two dots initially and medially: (یـ ـیـ ـی).

In Kashmiri, it uses a ring instead of dots below (ؠ) (ؠ ؠـ ـؠـ ـؠ‎).

In different calligraphic styles like the Hijazi script, Kufic, and Nastaʿlīq script, a final yāʾ might have a particular shape with the descender turned to the right (ـے), called al-yāʾ al-mardūdah/al-rājiʿah ("returned, recurred yāʾ"),[6] either with two dots or without them.[7]

In Urdu this is called baṛī ye ("big ye"), but is an independent letter used for /ɛː, eː/ and differs from the basic ye (choṭī ye, "little ye"). For this reason the letter has its own code point in Unicode. Nevertheless, its initial and medial forms are not different from the other ye (practically baṛī ye is not used in these positions).