The New Student's Reference Work/D

D (dē), the fourth letter, is a vocal consonant.  It is classed as a dental or hard palate sonant, because made by the point of the tongue against that palate or the front teeth, as in day, fixedness, old.  When preceded by a surd in the same syllable, d sounds as t, as in arched, hissed, looked.  It is silent in handkerchief, handsome, windrow and the first syllable of Wednesday.  The Romans used D as a numeral (500) as well as a letter.