Greek Capital Letter Delta

A triangular uppercase Greek letter used far beyond Greek text, Greek Capital Letter Delta at U+0394 belongs to the Greek and Coptic block. In modern Greek it is the capital form of delta, pronounced like the voiced “th” in English “this,” and it appears in names, headings, acronyms, and alphabetic ordering wherever Greek is written. Its most familiar technical use is to mark change or difference in mathematics, science, and engineering. Δx means a change in x, Δt an elapsed time, ΔT a temperature difference, and ΔG in chemistry commonly denotes a change in Gibbs free energy. In geometry, the same letter can label a triangle, and in calculus a capital delta often signals a finite difference rather than an infinitesimal one. The letter also appears in specialist notation and symbols: finance uses delta for the sensitivity of an option’s price to the underlying asset, while physics and engineering use it in terms such as Laplacian-related notation or delta-connected electrical systems. Because its shape resembles a plain triangle, it is sometimes confused with triangle symbols, but in formal text it is a Greek letter with alphabetic meaning.