D

D¹

(also d)

noun (plural Ds or D's)

1》 the fourth letter of the alphabet.

2》 denoting the fourth in a set of items, categories, sizes, etc.

3》 Music the second note of the diatonic scale of C major.

4》 the Roman numeral for 500. [understood as half of CI, an earlier form of M (= 1,000).]

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D²

abbreviation

1》 (in the US) Democrat or Democratic.

2》 depth (in the sense of the dimension of an object from front to back).

3》 Chemistry dextrorotatory.

4》 (with a numeral) dimension(s) or dimensional.

5》 (in tables of sports results) drawn.

6》 Germany (international vehicle registration). [from Ger. Deutschland.]

symbol

1》 Physics electric flux density.

2》 Chemistry the hydrogen isotope deuterium.