D

D is a letter of the Latin (Roman) alphabet, the script now used to write English and most languages of western Europe and, today, much of the world. It represents the voiced stop /d/. Historically it is from Phoenician daleth ('door') by way of Greek delta. Unlike the Hebrew and Greek alphabets, the Latin (Roman) alphabet never developed a systematic per-letter mystical or numerological tradition: Roman numerals form a separate, non-alphabetic system, so this entry stays with the letter's linguistic and historical record. The Roman alphabet is the youngest of the three historical scripts covered in this atlas: Latium adapted it around the 7th century BCE from a west Greek alphabet, reaching it through Etruscan intermediaries who had themselves taken their letters from Greek colonists settled in the bay of Naples. Latin calls each letter simply by its sound rather than by an inherited name, unlike Hebrew and Greek, and it never built an alphabetic numeral system of its own, so there is no ancient Latin counterpart to Hebrew gematria or Greek isopsephy; Roman numerals are a separate, non-alphabetic notation.

A modern practice called name numerology, drawn from a twentieth-century repeating 1-to-9 chart and commonly marketed as Pythagorean despite no documented link to Pythagoras, assigns the letter D the digit 4; a rival popular scheme, the so-called Chaldean system, assigns different digits to the same letters, so even the two modern schemes disagree with each other.

The Latin D's sound history, back through Phoenician dalet and Greek delta, is covered elsewhere; this entry follows the letter's outline. Dalet was drawn as a simple triangle, meaning door, and Greek delta preserved that triangular shape almost unchanged, giving classical Greek its familiar angular capital. Etruscan and Roman scribes, working in a script built more from curves than the Greek monumental alphabets, rounded delta's triangle into a bow set against a straight vertical stroke, producing the D shape already fixed in Roman inscriptions by the classical period. That silhouette has proven remarkably stable: the lowercase d that emerged through Roman cursive and later uncial handwriting simply extended the vertical stroke upward into an ascender while keeping the bow low, and that structure passed into the Carolingian minuscule of the 9th century essentially unchanged from the capital's own logic.

D also serves as a Roman numeral, worth five hundred; unlike I, V and X, its numeral value is not explained by any tally-notch ancestry, and one common account derives the symbol as half of an older sign for one thousand split along its vertical stroke, though, as with several of the larger Roman numerals, the derivation is not settled with certainty.