I with diaeresis (Cyrillic)

Slavic letters
А Б В Г Ґ Д Ђ Ѓ Е Ѐ Ё Є Ж З Ѕ И Ѝ І Ї Й Ј К Л Љ М Н Њ О П Р С Т Ћ Ќ У Ў Ф Х Ц Ч Џ Ш Щ Ъ Ы Ь Э Ю Я
Non-Slavic letters
Ӑ А̄ А̊ А̃ Ӓ Ӓ̄ Ә Ә́ Ә̃ Ӛ Ӕ Ғ Г̧ Г̑ Г̄ Ҕ Ӻ Ӷ Ԁ Ԃ Ꚃ Ꚁ Ꚉ Ԫ Ԭ С́ Ӗ Е̄ Е̃ Ё̄ Є̈ Ӂ Җ Ꚅ Ӝ Ԅ Ҙ Ӟ З́ Ԑ Ԑ̈ Ӡ Ԇ Ӣ И̃ Ҋ Ӥ Қ Ӄ Ҡ Ҟ Ҝ Ԟ Ԛ Ӆ Ԯ Ԓ Ԡ Ԉ Ԕ Ӎ Ӊ Ң Ԩ Ӈ Ҥ Ԣ Ԋ О̆ О̃ О̄ Ӧ Ө Ө̄ Ӫ Ҩ Ԥ Ҧ Р̌ Ҏ Ԗ Ҫ Ԍ Ꚑ Ҭ Ꚋ Ꚍ Ԏ У̃ Ӯ Ӱ Ӱ́ Ӳ Ү Ү́ Ұ Х̑ Ҳ Ӽ Ӿ Һ Һ̈ Ԧ Ꚕ Ҵ Ꚏ Ҷ Ӵ Ӌ Ҹ Ꚓ Ꚗ Ꚇ Ҽ Ҿ Ы̆ Ы̄ Ӹ Ҍ Э̆ Э̄ Э̇ Ӭ Ӭ́ Ӭ̄ Ю̆ Ю̈ Ю̈́ Ю̄ Я̆ Я̄ Я̈ Ԙ Ԝ Ӏ
Archaic letters
Ꙁ Ꙃ Ꙅ Ꙇ Ꙉ Ҁ Ѻ ОУ Ꙋ Ѡ Ѽ Ꙍ Ѿ Ꙏ Ѣ Ꙑ Ꙓ Ꙕ Ꙗ Ѥ Ѧ Ꙙ Ѫ Ꙛ Ѩ Ꙝ Ѭ Ѯ Ѱ Ѳ Ѵ Ѷ Ꙟ Ꙡ Ꙣ Ꙥ Ꙧ Ꙩ Ꙫ Ꙭ ꙮ Ꚙ Ꚛ
List of Cyrillic letters Cyrillic digraphs

I with diaeresis (Ӥ ӥ; italics: Ӥ ӥ) is a letter of the Cyrillic script. It is used only in the Udmurt language where it represents the close front unrounded vowel /i/, and is used only after the non-palatalized dentals /d/, /z/, /l/, /n/, /s/ and /t/; the Cyrillic letter I (И и) is used otherwise.

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Wikipedia