D definition and meaning | Collins English Dictionary (2025)

D

also d (diː ) (plural D's, d's )

1.variable noun A1

D is the fourth letter of the English alphabet.

2.variable noun

In music, D is the second note in the scale of C major.

3.variable noun B1+

If you get a D as a mark for a piece of work or in an exam, your work is below average or poor.

I got a D+.

d. is an abbreviation for died when it is written in front of dates, for example on graves or in reference books.

d was a written abbreviation for penny or pence in Britain before decimal currency was introduced in 1971.

D or d is used as an abbreviation for words beginning with d, such as 'day', 'defeated', or ' district'.

English Easy Learning GrammarWhen do you use 'would' in English?The modal verbwouldis commonly used as follows:
to make a polite request.
Wouldyou mind moving your bag?
Wouldyougive me a hand with this ladder, ...Read more

d'

(d- )

d'you

-'d

pronunciation note: Pronounced (-d ) after a vowel sound and (-əd ) after a consonant sound.

-'d is a spoken form of 'had', especially when 'had' is an auxiliary verb. It is added to the end of the pronoun which is the subject of the verb. For example, 'you had' can be shortened to 'you'd'.

-'d is a spoken form of 'would'. It is added to the end of the pronoun which is the subject of the verb. For example, 'I would' can be shortened to 'I'd'.

d in British English 1

or D (diː )

nounWord forms: plural d's, D's or Ds

the fourth letter and third consonant of the modern English alphabet

a speech sound represented by this letter, usually a voiced alveolar stop, as in dagger

the semicircle on a billiards table having a radius of 111⁄2 inches and its straight edge in the middle of the baulk line

d in British English 2

symbol for

1. physics

density or relative density

2. mathematics

a small increment in a given variable or function: used to indicate a derivative of one variable with respect to another, as in d y/d x

3. chess See algebraic notation

D in British English 1

symbol for

1. music

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

a key, string, or pipe producing this note

the major or minor key having this note as its tonic

2. chemistry

deuterium

3. mathematics

the first derivative of a function, as in D(x3 + x2) = 3x2 + 2x

4. physics

dispersion

electric displacement

5. aeronautics

drag

a semiskilled or unskilled manual worker, or a trainee or apprentice to a skilled worker

(as modifier)

D worker

D in British English 2

or D.

abbreviation for

Deutsch: indicating the serial number in the catalogue (1951) of the musical compositions of Schubert made by Otto Deutsch (1883–1967)

d. in British English

abbreviation for

(in animal pedigrees) dam

daughter

3. British currency

penny or pennies

diameter

died

dinar(s)

dollar(s)

drachma(s)

Word origin

(sense 3 and 6) Latin denarius

D. in British English

abbreviation for

1. US politics

Democrat(ic)

2. government

Department

dinar(s)

Don (a Spanish title)

Duchess

Duke

(in the US and Canada) Doctor

'd in British English

contraction of

would or had

I'd

you'd

D in American English 1

(di )

noun

a Roman numeral for 500; with a superior bar (), 500,000 or less often, 5,000

2. US, Education

a grade indicating below-average work, or merely passing

3. Music

the second tone or note in the ascending scale of C major

a key, string, etc. producing this tone

the scale having this tone as the keynote

adjective

below average in quality

D in American English 2

dairy: prepared according to kashrut or kosher laws

December

Democrat

Democratic

5. Chemistry

deuterium

digital

drive (on automotive automatic-shift indicators)

Doctor

Don

10.

Duchess

11.

Duke

12.

Dutch

13.

Lord

Word origin

(sense 13) L Dominus

d in American English 1

(di ) or D (di )

nounWord forms: plural d's or D's

the fourth letter of the English alphabet: from the Greek delta, a borrowing from the Phoenician

any of the speech sounds that this letter represents, as, in English, the (d) of dog

a type or impression for d or D

the fourth in a sequence or group

an object shaped like D

adjective

of d or D

fourth in a sequence or group

shaped like D

d in American English 2

dam (in pedigrees)

date

daughter

day(s)

dead

deci-

degree

8. Physics

density

departs

10.

departure

11.

diameter

12.

died

13. Physics

distance

14.

division

15.

dollar

16.

dorsal

17.

dose

18.

dyne(s)

19. Pharmacy

give

20.

penny; pence

Word origin

(sense 19) L da; (sense 20) L denarius, pl. denarii

D- in American English

(di )

having an asymmetrical, right-handed spatial arrangement of atoms: usually printed as a small capital

D-glucose

d'- in American English

d'you know the story?

d- in American English

(di )

dextrorotatory

usually printed in italic type [d-limonene] or, now, symbolized by a plus sign (+)

-'d in American English 1

had

I'd seen it before

would or should

we said we'd help

did

how'd you get here?

-'d in American English 2

-ed used

esp. in old poetry, to indicate a nonsyllabic ending

foster'd

to spell the inflected forms of some words, esp. initialisms

mascara'd, OD'd

D in American English 1

abbreviation

1.Electricity debye

deep

depth

4.Optics

diopter

divorced

Dutch

D in American English 2

symbol

the fourth in order or in a series

2.(sometimes lc; 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 lc)

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

d.(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 lc)

the Roman numeral for 500

Compare Roman numerals

6.Chemistry

deuterium

7.Electricity

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

a symbol for a shoe width size narrower than E and wider than C

10.

a proportional brassiere cup size larger than C

D in American English

(di) d (di)

nounWord forms: plural D's or Ds, d's or ds

the fourth letter of the English alphabet, a consonant

any spoken sound represented by the letter D or d, as in dog, ladder, ladle, or pulled

something having the shape of a D.

a written or printed representation of the letter D or d

a device, as a printer's type, for reproducing the letter D or d

d. in American English

abbreviation

1.(in prescriptions)

give

date

daughter

day

deceased

deep

degree

delete

9.Brit

pence

10.Brit

penny

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

Word origin

[(def. 1) ‹ L dā; (def. 9) ‹ L denāriī; (def. 10) ‹ L denārius]

D. in American English

abbreviation

day

December

Democrat

Democratic

5.Physics

density

Deus

Deuteronomy

Doctor

dose

10.

Dutch

d' in American English 1

preposition

(used in French names as an elided form of de)

Charles Louis d'Albert

(used in Italian names as an elided form of di)

Gabriele d'Annunzio

d' in American English 2

(pronunciation spelling)

contraction of

do or did (before you)

How d'you like your eggs cooked?

D'you go to the movies last night?

'd in American English

contraction of

had

I was glad they'd gone

did

Where'd they go?

should or would

He'd like to go

I'd like to remind you of your promise

-ed

She OK'd the plan

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