The letter D is the fourth letter of the Latin alphabet.

History

The Semitic letter Dâlet probably developed from the logogram for a fish or a door. In Semitic, Ancient Greek (Modern Greek /ð/) and Latin the letter was pronounced /d/, in the Etruscan alphabet the letter was superfluous but still maintained (see letter B). Greek letter: Δ (capital) or δ (small) (Delta).

Usage

The letter D generally takes the voiced alveolar plosive value, IPA in most languages that use the Roman alphabet, including English. In Welsh d when doubled (dd) has the value /ð, like English th in this.

Digraphs of D are rare in English, although other languages use DH or DD for a voiced dental fricative (some Celtic languages) or an aspirated voiced dental plosive (some Indo-Aryan languages), or use affricates DZ, DV, or DZH.

In Cantonese, the sound /d/ means a little bit, from the ancient use of the character 的 (in the phrase "兀的") in Chinese written language. Since 的 is no longer used in this way, Hong Kong residents invented a new character 啲 (which is not supported in many Chinese systems), or simply write D instead.

Alternate representations

Delta represents the letter D in the NATO phonetic alphabet, except in airports, to avoid confusion with Delta Air Lines, in which case it is Dixie.

In international Morse code the letter D is DahDitDit: - · ·

In Braille the letter D is represented as ⠙ (in Unicode), the dot pattern,

XX
.X
..

Computing

In Unicode the capital D is codepoint U+0044 and the lowercase d is U+0064.

The ASCII code for capital D is 68 and for lowercase d is 100; or in binary 01000100 and 01100100, correspondingly.

The EBCDIC code for capital D is 196 and for lowercase d is 132.

The numeric character references in HTML and XML are "D" and "d" for upper and lower case respectively.

Meanings for D

• In the atmosphere of Earth, the D layer is part of the ionosphere.
• In biochemistry, D is the symbol for aspartic acid.
• In calendars, D is often an abbreviation for the month December.
• In chemistry, D is the symbol of deuterium, an isotope of hydrogen.
• In computing, D is the name of a programming language; see D programming language.
• In driving a motor vehicle, D (drive) designates the forward cruising gears in an automatic transmission.
• In economics, D is stands for demand.
• In education, D is a barely passing grade.
• In electronics, D is a standard size dry cell battery.
• In finance securities, D is the stock symbol for Dominion Resources Inc. VA
• In geometry, d is often a variable for the diameter of a circle.
• In international licence plate codes, D stands for Germany.
• In mathematics,
  • d is the symbol for the differential operator.
  • D is often used as a digit meaning thirteen in hexadecimal and other positional numeral systems with a radix of 14 or greater.
• In the Metric system, d, deci, is the SI prefix meaning one tenth, 10^-1.
• In music, D is a note.
• In nutrition, D is a vitamin.
• In print, D Magazine is a magazine for the city of Dallas, Texas.
• In Roman numerals, D denotes 500.
• In British currency, d is an abbreviation for the pre-decimalization pence, worth 1/240th of a pound.
• In basketball, D is often used as an abbreviation for Defence.

See also

• Ð