Definition of diacritical in English:

diacritical

adjective

  • (of a mark or sign) serving to indicate different pronunciations of a letter above or below which it is written.

    • ‘Where necessary, I have adapted Italian and Latin texts according to modern convention, spelling out abbreviations, adding diacritical marks, and replacing u for v and i for j.’
    • ‘In modern written Vietnamese, which uses the romanized system of writing introduced by European missionaries, the tones are indicated by diacritical marks, or marks written above and below the vowel in each syllable.’
    • ‘Here are some useful sites for anyone needing to display diacritical marks, mathematical symbols, etc.’
    • ‘Slovak, like other Slavic languages, has diacritical marks that govern the pronunciation of both consonants and vowels.’
    • ‘The present orthographic system was introduced in the fourteenth century by the religious reformer Jan Hus, who instituted a system of diacritical markings to eliminate consonant clusters.’

Pronunciation

diacritical

/ˌdʌɪəˈkrɪtɪk(ə)l/