THE LETTER D OF THE ALPHABET. This letter has retained the fourth place in the alphabet from the earliest point at which it pears in history. It corresponds to Semitic d (daleth) and Greek A (delta). The rounded form D occurs in the Chalcidic alphabet, from which it passed into the Latin, as well as in the Etruscan. The Umbrian and Oscan forms, written from right to left, are re spectively 9 and 54 . The letter has retained the rounded form that it had in the Latin alphabet until the present day.
The sound consistently represented by the letter in Semitic, Greek, Latin, and the modern languages of Europe is the voiced dental stop. In English this sound, as well as the unvoiced sound represented by t, has become alveolar, that is to say, is pronounced by the pressure of the tongue upon the gums rather than upon the teeth.
In music, D is the fourth note of the musical alphabet and the second note of the scale of C. In former times it gave its name also to one of two or three clefs which are now no longer in use. (See CLEF.) Used as an abbreviation, D has several meanings, e.g., m.d.=main droite; d.c. = da capo; d.s. =dal segno.