- a mapping of a function, as a signal, that is defined in one domain, as space or time, into another domain, as wavelength or frequency, where the function is represented in terms of sines and cosines. Abbreviation: FT
- an integral transform, used in many branches of science, of the form F(x) = [1/√(2π)]ʃe i xy f(y)d y, where the limits of integration are from –∞ to +∞ and the function F is the transform of the function f
