Dotted dhal

Dotted dhal or dal-i mu'ajjam (دال معجم, literally "Persianized dal") refers to the Arabic letter dhal (ذ).

More specifically, it also refers to a feature of the early forms of the New Persian language and a practice followed by its writers, who used the letter dhal (ذ), pronounced like th in the English word mother, in lieu of dal (د) in middle of the word when the dal is preceded and followed by a vowel, or when dal was in the final position and preceded by a vowel.