Is it ensure, insure, or assure?
fourth letter of the Roman alphabet, from Greek delta, from Phoenician and Hebrew daleth, pausal form of deleth "door," so called from its shape. The sign for "500" in Roman numerals. 3-D for "three-dimensional" is attested from 1953.
The symbol for the isotope deuterium.
Relating to the configuration of d-glyceraldehyde, a compound chosen as the basis for stereochemical nomenclature because it is the simplest carbohydrate that can form optical isomers: d-fructose.
d- pref. d-
To the right; dextro: d-tartaric acid.
Abbreviation of diameter