D

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D is the fourth (number 4) letter in the alphabet. It comes from the Greek Delta and the Phoenician Dalet.

 Meanings for D 
 In education, D is one letter above a failing grade.
 In electronics, D is a standard size dry cell battery.
 In music, D is a note sometimes called “Re”.
 In Roman numerals, D also means the number 500.
 In computer programming, D is a programming language.

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