Dda: The Voiced Retroflex, and the Dotted Letter Beside It

Dda is the thirteenth consonant of the varnamala, the voiced unaspirated retroflex and the third member of the third varga, standing to the class's first letter as ga stands to ka. In the modern languages written with Devanagari the same sign also carries a dot beneath it to write a distinct sound, a flap produced by striking the curled tongue tip against the roof of the mouth as it moves forward, which classical Sanskrit did not treat as a separate consonant. That dotted letter is a post-classical addition to the script, and it belongs to a small group of such additions made for sounds the varnamala had no place for, several of them arriving with Persian and Arabic vocabulary.

The mechanism is consistent: rather than reorder or extend the table, the script marks the new sound as a modification of the nearest existing letter, so the classical arrangement survives intact and the additions are visibly outside it. That is a design decision with consequences. It keeps the varnamala usable as a shared reference across every language that writes in Devanagari, and it makes the history of the script legible on the page, since a reader can see at a glance which signs belong to the original analysis and which were added later.