Delta

From Textus Receptus

Δ δ Delta

Delta (uppercase Δ, lowercase δ; Greek: Δέλτα [ðelta] Thelta) is the fourth letter of the Greek alphabet. In the system of Greek numerals it has a value of 4. It was derived from the Phoenician letter Dalet, but in the Ancient Greek language..

A river delta is so named because its shape approximates the upper-case letter delta.