Noun
Haar wavelet (plural Haar wavelets)
A sequence of rescaled "square-shaped" functions which together form a wavelet family or basis.
The Haar wavelet is also the simplest possible wavelet. Source: Internet
This transform cross-multiplies a function against the Haar wavelet with various shifts and stretches, like the Fourier transform cross-multiplies a function against a sine wave with two phases and many stretches. Source: Internet