Delta \del"ta\, n.; pl. deltas [Gr. delta, the name of the fourth letter of the Greek alphabet (the capital form of which is (), Eng. D), from the Phoenician name of the corresponding letter. The Greeks called the alluvial deposit at the mouth of the Nile, from its shape, the Delta of the Nile.]

1. The fourth letter of the Greek alphabet (), answering to D. Hence, an object having the shape of the capital ()
2. (Elec.) The closed figure produced by connecting three coils or circuits successively, end for end, esp. in a three-phase system; -- often used attributively, as delta winding, delta connection (which see), etc
3. A tract of land shaped like the letter delta (), especially when the land is alluvial and inclosed between two or more mouths of a river; as, the delta of the Ganges, of the Nile, or of the Mississippi