1. the fourth letter of the modern english alphabet.
2. any of the speech sounds represented by the letter d.
3. the fourth in a series.
4. something shaped like the letter D.
5. the lowest passing grade given to a student in a school or college.
6. music the second tone in the scale of C major or the fourth tone in the relative minor scale.
7. music A key or scale in which D is the tonic.
8. music A written or printed note representing this tone.
9. music A string, key, or pipe tuned to the pitch of this tone.
10. deuteron
11. diameter
12. differential
13. down quark

1. the fourth letter of the basic modern latin alphabet.
2. cardinal number five hundred (500).
3. the differential of a quantity
4. voiced alveolar plosive
5. the fourth letter of the english alphabet, called dee and written in the latin script.
6. the ordinal number fourth, derived from this letter of the english alphabet, called dee and written in the latin script.
7. died, death.
8. declared; also abbreviated as dec
9. a british penny; an old penny (the modern decimal penny being abbreviated p).
10. dice to use in a diceroll
11. penny, a measure of the size of nails

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. see guide to pronunciation, √178, 179, 229.
2. 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.

1. the fourth letter and third consonant in the english alphabet: the corresponding character has the same position and the same value also in the latin, greek, and Phenician alphabets, from which it comes to us. (see A.)
2. as a numeral, in the roman system,
3. as a symbol: in music: the second tone, or re, of the scale of C.
4. A note which represents this tone.
5. the key-note of the key of two sharps .
6. on the keyboard of the organ or pianoforte, the white key or digital included in each group of two black keys.
7. the string in a stringed instrument that is tuned to the tone D, as the third string of the violin, etc. in chem.,
8. in mathematics, d is the sign of differentiation, ∂ of partial differentiation,
9. in the mnemonic words of logic, the sign of reduction to darii.
10. as an abbreviation: in eng. reckoning (d. or d.), an abbreviation of denarius, the original name for the english penny: as, £ s. d., pounds, shillings, and pence; 2s. 1d., two shillings and one penny.
11. before a date (d.), an abbreviation of died.
12. in dental formulas, an abbreviation of deciduous, prefixed without a period to the letters i, c, and m: thus, di., deciduous incisor; dc., deciduous canine; dm., deciduous molar: all being teeth of the milk-dentition of a diphyodont mammal.
13. or, more simply, taking one half of each jaw only, di. , dc. , dm. . in either case the numbers above the line are those of the upper teeth, and those below the line of the under teeth. see dental.
14. in anatomy and ichthyology (d. or D.), an abbreviation of dorsal (vertebra or fin, respectively).
15. in a ship's logbook (d.), an abbreviation of drizzling.
16. A form of -ed, -ed, in certain words. see -ed, -ed.
17. an abbreviation of the latin defensor fidei, defender of the faith. see defender.
18. an abbreviation of the latin Dei gratia, by the grace of god.
19. an abbreviation of dead-reckoning.
20. in music: also, the key-note of the minor key medieval music, the final of the dorian and Hypodorian modes.
21. in chem.: d- before certain compounds has reference to their behavior toward polarized light, namely, to their dextrorotation, as distinguished from their inaction (i-) or levorotation (l-).
22. in mathematics: D is also used for the number denoting the deficiency of a curve (what its number of double points lacks of the maximum).
23. as an abbreviation: in law (D.), an abbreviation of decree, Decret, dictum.
24. in medicine (d.), an abbreviation of: diopter or dioptric;
25. dexter (right.);
26. divide (in prescriptions).
27. (D.) of democrat, deus (god), dominus (lord), dutch; (d.) of daughter, delete (cancel), density.
28. short for damn (often printed d—).
29. any mechanical device or appliance which resembles the letter
30. an abbreviation of dean of the faculty.
31. an abbreviation of deadhead or deadheaded.
32. an abbreviation of doctor of oratory
33. of doctor of osteopathy.
34. an abbreviation of doctor of pharmacy.
35. in electricity, an abbreviation for double pole.
36. in music, an abbreviation of da capo.
37. an abbreviation of latin (ML.) divinitatis doctor, doctor of divinity.
38. in music, an abbreviation of destra mano (which see).
39. abbreviations of doctor of music.
40. an abbreviation of dal segno.
41. an abbreviation of the latin Deo volente, god willing. see Deo volente.
42. an abbreviation of doomsday book.
43. an abbreviation of direct current;
44. of district court;
45. of district of columbia;
46. of deputy consul;
47. of Divus Cæsar (the divine Cæsar).
48. an abbreviation of dynamical engineer, a degree conferred at the completion of a graduate course in mechanical engineering.
49. an abbreviation of deputy lieutenant;
50. of doctor of law, a degree equivalent to D. C. L.
51. of doctor of literature, a degree equivalent to D. lit.
52. an abbreviation of doctor of science.
53. abbreviations of doctor of theology.
54. an abbreviation of delirium tremens.
55. in electricity, of double-throw: as, a d. t. switch.

1. the 4th letter of the roman alphabet
2. denoting a quantity consisting of 500 items or units
3. a fat-soluble vitamin that prevents rickets
4. the cardinal number that is the product of one hundred and five