d /ˈdi/
 字母D
 D
 1. The fourth letter of the English alphabet, and a vocal consonant. The English letter is from Latin, which is from Greek, which took it from Phœnician, the probable ultimate origin being Egyptian. It is related most nearly to t and th; as, Eng. deep, G. tief; Eng. daughter, G. tochter, Gr. qyga`thr, Skr. duhitr. See Guide to Pronunciation, √178, 179, 229.
 2. Mus. The nominal of the second tone in the model major scale (that in C), or of the fourth tone in the relative minor scale of C (that in A minor), or of the key tone in the relative minor of F.
 3. As a numeral D stands for 500. in this use it is not the initial of any word, or even strictly a letter, but one half of the sign ░ (or ░ ) the original Tuscan numeral for 1000.
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 d
      adj : denoting a quantity consisting of 500 items or units [syn: five
            hundred, 500]
      n 1: a fat-soluble vitamin that prevents rickets [syn: vitamin D,
            calciferol, viosterol, ergocalciferol, cholecarciferol]
      2: the cardinal number that is the product of one hundred and
         five [syn: five hundred, 500]
      3: the 4th letter of the Roman alphabet