1. n. (also d) (pl. Ds or D's)
1. the fourth letter of the alphabet.
2 Mus. the second note of the diatonic scale of C major.
3 (as a Roman numeral) 500.
5 the fourth highest class or category (of academic marks etc.). 2.
symb. Chem. the element deuterium. 3. abbr. (also D.)
1. US Democrat.
2 dimension (3-D).