Meaning

noun a low triangular area of alluvial deposits where a river divides before entering a larger body of water

noun an object shaped like an equilateral triangle

noun the 4th letter of the Greek alphabet

originFrom Ancient Greek δέλτα (délta), borrowed from a Phoenician word for "door", ultimately from Proto-Semitic *dalt-. Doublet of dalet. * (river): from the triangular shape of the majuscule Greek letter delta Δ * (USSF): from the delta wing, symbol of the USSF, a triangular wing, shaped like the majuscule Greek letter delta Δ

Etymology from Wiktionary, CC BY-SA 3.0