delta

delta¹

noun

1》 the fourth letter of the Greek alphabet (Δ, δ), transliterated as ‘d’.

    ↘[as modifier] denoting the fourth in a series of items or categories.

    ↘Brit. a fourth-class mark given for a piece of work.

2》 a code word representing the letter D, used in radio communication.

symbol Mathematics variation of a variable or quantity.

Origin

Gk, from Phoenician daleth.

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delta²

noun a triangular tract of sediment deposited at the mouth of a river, typically where it diverges into several outlets.

Derivatives

deltaic adjective

Origin

C16: orig. the Delta (of the River Nile), from the shape of the Gk letter (see delta¹).