d, letter that has retained the fourth place in the alphabet from the earliest point at which it appears in history. It corresponds to Semitic daleth and Greek delta (Δ). The form is thought to derive from an early pictograph, possibly Egyptian, indicating the folding door of a tent., D, d (di) n., pl. Ds D's, ds d's. 1. the fourth letter of the English alphabet, a consonant. 2. any spoken sound represented by this letter., Quasi-Latinate spellings with d became conventional, and pronouncing the d followed, even where the inserted letter was etymologically spurious: for example, admiral derives from Arabic amir (commander), and advance from Latin abante (from before: compare Italian avanti)., Unetymological -d- is the result of a tendency in English and neighboring languages, perhaps for euphony, to add -d- to -n-, and especially to insert or swap a -d- sound when -l- or -r- follow too closely an -n-., D, or d, is the fourth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide., Any of the speech sounds that this letter represents, as, in English, the (d) of dog..