D

UK: 'D', 'd': /ˈdiː/ US: 'D', 'd': /di/ ,'D', 'd': (dē)

Collins Concise English Dictionary © HarperCollins Publishers::

D symbol

1. a note having a frequency of 293.66 hertz (D above middle C) or this value multiplied or divided by any power of 2; the second note of the scale of C major
2. a key, string, or pipe producing this note
3. the major or minor key having this note as its tonic
4. deuterium
5. a semiskilled or unskilled manual worker, or a trainee or apprentice to a skilled worker
6. (as modifier): D worker
   See also occupation groupings
7. (Roman numeral) 500
   See Roman numerals

Etymology: (for sense 8) from German Deutschland

WordReference Random House Learner's Dictionary of American English © 2025

D, d /di/   n. [countable] , pl. Ds or D's, ds or d's. 

1. Linguistics the fourth letter of the English alphabet, a consonant.
2. Education [sometimes: d] (in some grading systems) a grade or mark indicating poor or barely acceptable quality.

d',²  [Pron. Spelling.]

1. do (esp. before you):
   How d'you like them?

'd, 

1. contraction of
   had: They'd already left.
2. contraction of
   would: I'd like to see it.
3. contraction of did: Where'd you go?
4. contraction of -
   ed: She OK'd the plan.

D,  Symbol.

1. [sometimes: d] the Roman numeral for 500.

D.,  an abbreviation of:

1. day.
2. December.
3. Democrat.
4. Democratic.
5. Doctor.

d.,  an abbreviation of:

1. date.
2. daughter.
3. day.
4. deceased.
5. diameter.
6. died.

WordReference Random House Learner's Dictionary of American English © 2025

ˈRo•man ˈnu•mer•al,  n. [countable]

1. any of the numerals in the ancient Roman system of notation, still used occasionally. The basic symbols are I (=1), V (=5), X (=10), L (=50), C (=100), D (=500), and M (=1000).

WordReference Random House Unabridged Dictionary of American English © 2025

D, d  (dē), n., pl. D's or Ds, d's or ds. 

1. the fourth letter of the English alphabet, a consonant.
2. any spoken sound represented by the letter D or d, as in dog, ladder, ladle, or pulled.
3. something having the shape of aD.
4. a written or printed representation of the letter D or d.
5. a device, as a printer's type, for reproducing the letter D or
   d.

d-, 

1. Biochemistry [Symbol, Biochem.] (of a molecule) having a configuration resembling the dextrorotatory isomer of glyceraldehyde: always printed as a small capital, roman character (distinguished from l-). Cf. d-.

d-, [Symbol, Chem., Biochem.]

1. Chemistry, Biochemistry dextrorotatory;
   dextro- (distinguished from l-). Cf. D-.

d'¹ ,prep. 

1. Foreign Terms de (used in French names as an elided form of de):
   Charles Louis d'Albert.
2. Foreign Terms di (used in Italian names as an elided form of di):
   Gabriele d'Annunzio.

d'² ,

1. Grammar [Pron. Spelling.] contraction of do or did before you:
   How d'you like your eggs cooked? D'you go to the movies last night?

'd, 

1. contraction of had: I was glad they'd gone.
2. contraction of did: Where'd they go?
3. contraction of should or
   would: He'd like to go. I'd like to remind you of your promise.
4. contraction of -ed: She OK'd the plan.

D, 

1. [Elect.] debye.
2. Education deep.
3. depth.
4. Music and Dance, Optics [Optics.] diopter.
5. divorced.
6. Chemistry Dutch.

D,  Symbol.

1. the fourth in order or in a series.
2. (sometimes l.c.) (in some grading systems) a grade or mark, as in school or college, indicating the quality of a student's work as poor or barely passing.
3. (sometimes l.c.) a classification, rating, or the like, indicating poor quality.
4. [Music.]
   • the second tone in the scale of C major, or the fourth tone in the relative minor scale, A minor.
   • a string, key, or pipe tuned to this tone.
   • a written or printed note representing this tone.
   • (in the fixed system of solmization) the second tone of the scale of C major, called re.
   • the tonality having D as the tonic note.
5. (sometimes l.c.) the Roman numeral for 500. Cf. Roman numerals.
6. [Chem.] deuterium.
7. [Elect.]
   • electric displacement.
   • a battery size for 1.5 volt dry cells: diameter, 1.3 in. (3.3 cm);
     length, 2.4 in. (6 cm).
8. Biochemistry aspartic acid.
9. Clothing a symbol for a shoe width size narrower than E and wider than C.
10. Clothing a proportional brassiere cup size larger than C.

D., 

1. day.
2. December.
3. Democrat.
4. Democratic.
5. Physics density.
6. Religion Deus.
7. Bible Deuteronomy.
8. Doctor.
9. dose.
10. Dutch.

d., 

1. (in prescriptions) give.
• Latin dā
2. date.
3. daughter.
4. day.
5. deceased.
6. deep.
7. degree.
8. delete.
9. British Terms, Currency pence.
• Latin dā
10. British Terms, Currency penny.
• Latin dā
11. Physics density.
12. depth.
13. deputy.
14. dialect.
15. dialectal.
16. diameter.
17. died.
18. dime.
19. dividend.
20. dollar;
    dollars.
21. dose.
22. drachma.

WordReference Random House Unabridged Dictionary of American English © 2025

O•ke•ghem  (ō′kə gem′), n. 

Jean  (zhän) d' or Jan van  (yän vän), c1430–c95, Flemish composer.Also, Ockeghem, Ockenheim. 

WordReference Random House Unabridged Dictionary of American English © 2025

Ro′man nu′merals, 

1. the numerals in the ancient Roman system of notation, still used for certain limited purposes, as in some pagination, dates on buildings, etc. The common basic symbols are I (=1), V (=5), X (=10), L (=50), C (=100), D (=500), and M (=1000). The Roman numerals for one to nine are: I, II, III, IV, V, VI, VII, VIII, IX. A bar over a letter multiplies it by 1000;
   thus, X̄ equals 10,000. Integers are written according to these two rules: If a letter is immediately followed by one of equal or lesser value, the two values are added;
   thus, XX equals 20, XV equals 15, VI equals 6. If a letter is immediately followed by one of greater value, the first is subtracted from the second;
   thus, IV equals 4, XL equals 40, CM equals 900. Examples: XLVII(=47), CXVI(=116), MCXX(=1120), MCMXIV(=1914). Roman numerals may be written in lowercase letters, though they appear more commonly in capitals.

• 1725–35

Collins Concise English Dictionary © HarperCollins Publishers::

d, D / diː/ noun (d's, D's, Ds)

1. the fourth letter and third consonant of the modern English alphabet

d symbol

1. density or relative density

Collins Concise English Dictionary © HarperCollins Publishers::

'd contraction

1. would or had: I'd, you'd

Collins Concise English Dictionary © HarperCollins Publishers::

D. abbreviation

1. Democrat(ic)
2. Department
3. Duchess

Collins Concise English Dictionary © HarperCollins Publishers::

d. abbreviation

1. (in animal pedigrees) dam
2. daughter
3. penny or pennies
4. diameter
5. died
6. dinar(s)
7. dollar(s)
8. drachma(s)

Etymology: (sense 3 and 6) Latin denarius