Iotation is a form of palatalisation which occurs in Slavic languages. In most of them, iotated consonants are called soft consonants and the process of iotation is called softening.

English singular	Serbian singular	Serbian plural
branch
leaf		/
stone	/	/

It occurs by the mixing of a consonant with the palatal approximant /j/, which is in the Greek alphabet represented by iota (ι), hence the name. For example, ni in English onion has the sound of iotated n. The example on the right shows how the Serbian language uses iotation to express the plural of a certain class of words.

An iotated consonant is represented in IPA with superscript j after it and in X-SAMPA with apostrophe after it, so the pronunciation of iotated n could be represented as or ^*.

As it was invented for the writing of Slavic languages, the Cyrillic alphabet has relatively complex ways for representing iotation, devoting an entire class of letters to deal with the issue; there are letters which represent iotified consonants as well as letters which iotify adjacent consonants or prevent their iotation. Their exact use depends on language; see Cyrillic alphabet as used in Slavic languages.

The adjective for a phone which undergoes iotation is iotated and for a letter formed as ligature of the Early Cyrillic I (І) and another letter, which is used to represent iotation, is iotified.

Iotified Cyrillic letters

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In the Cyrillic alphabet, some letter forms are iotified, that is, formed as a ligature of Early Cyrillic I (І) and a vowel.

Normal			Iotified			Comment
Name	Shape	Sound	Name	Shape	Sound
A	А	/a/	Iotified A	ІА	/ja/	Now supplanted by Ya (Я)
E	Е	/e/	Iotified E		/je/	No longer used
Uk	ОУ	/u/	Iotified Uk	Ю	/ju/	Uk is an archaic form of U (У)
Little Yus		/ẽ/	Iotified Little Yus		/jẽ/	No longer used
Big Yus		/õ/	Iotified Big Yus		/jõ/	No longer used

In old inscriptions, other iotified letters, even consonants, could be found, but these are not parts of a regular alphabet.

There are more letters which serve the same function, but their glyphs are not made in the same way.

Normal			Iotified			Comment
Name	Shape	Sound	Name	Shape	Sound
A	А	/a/	Ya	Я	/ja/
E	Э	/e/	Ye	Е	/je/	Used in Belarusian and Russian
E	Е		Ye	Є		Used in Ukrainian
I	І	/i/	Yi	Ї	/ji/	Used in Ukrainian
O	О	/o/	Yo	Ё	/jo/	Used in Belarusian and Russian

Cyrillic letters for iotated sounds

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Name	Shape	Sound
Dje	Ђ ђ
Gje	Ѓ ѓ
Lje	Љ љ
Nje	Њ њ
Tje	Ћ ћ
Kje	Ќ ќ

When Vuk Karadžić reformed the Serbian language (the system still largely influential over the Macedonian language), he created new letters which represent iotated consonants. This was possible because in Serbian and Macedonian only several consonants can be iotated. Though it might seem logical, the letters themselves are not called "iotated letters" or by any similar name.

See also

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• palatalization
• Cyrillic alphabet
• soft sign

Assimilation | Cyrillic alphabet

Jotacija | Jotacëjô | Jotyzacja