majhul

noun4

1. •
   A class of vowel used in various Arabic script languages, including Persian, Kurdish, and Urdu, among others.
2. •
   A vowel phoneme that does not have a phonemic equivalent in Classical Arabic.

   • The majhul sounds o and e are still preserved in the Persian spoken by Afghans and Indians, but they are now unknown in Persia. — 1919
3. •
   A semivowel, or other vocalic character, with a reading that is phonemically distinct from its normal pronunciation in Classical Arabic.
4. •
   A conditional allophone of a vowel phoneme that appears in proximity to certain guttural consonants.