Translation of "dieresis" into Welsh

(orthography) A diacritic ( ̈ ) placed over the second of two consecutive vowels to indicate that the second vowel is to be pronounced separately from the preceding vowel (as in the girls’ given name of Zoë ). It does not indicate a diphthong, but rather that each vowel has its full quality, within the sound-context. Now an uncommon practice in English, but still used in some other languages (e.g. French: haïr, Dutch: ruïne). [..]