D

Latin alphabet Aa Bb Cc Dd Ee Ff Gg Hh Ii Jj Kk Ll Mm Nn Oo Pp Qq Rr Ss Tt Uu Vv Ww Xx Yy Zz

The letter D is the fourth letter of the Latin alphabet. Its name in English is dee.

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).

The minuscule (lower-case) form of D, consisting of a loop and a tall vertical stroke, developed by gradual variations on the majuscule (capital) form. In handwriting it was common to start the arc to the left of the vertical stroke, resulting in a serif at the top of the arc. This serif was extended while the rest of the letter was reduced, resulting in an angled stroke and loop. The angled stroke then developed into a vertical stroke.

Usage

The letter D generally takes the voiced alveolar plosive value, IPA /d/ 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.

Alternative 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 British currency, d is an abbreviation (from the Latin denarius) for the pre-decimalization penny, worth 1/240th of a pound.
• 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 various programming languages, most notably the D programming language by Walter Bright.
  • D is a security division ("Minimal Protection") in the TCSEC.
• 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, D is the New York Stock Exchange ticker symbol for the Richmond, Virginia company Dominion.
• 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 total differential operator (partial differentials use ∂).
  • 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 SI system, d, deci, is the SI prefix meaning one tenth, 10^-1.
• In metrology, d is the symbol for day (from the Latin dies; this is the only symbol for this unit acceptable for use with SI)
• In music, D is a note.
• In nutrition, D is a vitamin.
• In particle physics, d is the symbol of the deuteron.
• In physics:
  • d is the recommended symbol for: thickness, diameter, relative density (mechanics), lattice plane spacing (solid state physics), and degeneracy of vibrational mode (molecular spectroscopy).
  • D is the recommended symbol for: diffusion coefficient (molecular physics), and Debye-Waller factor (solid state physics).
  • D is the recommended symbol for electric displacement (electricity and magnetism).
• In print, D Magazine is a magazine for the city of Dallas, Texas.
• In Roman numerals, D denotes the number 500 (there are also separate Unicode characters for this number, 0x216E "Ⅾ" and 0x217E "ⅾ").
• In sports, D is often used as an abbreviation for defence.
• In American politics, D is often used as an abbreviation for a Democrat.

See also

• Ð