(n)a change (usually undesired) in the waveform of an acoustic or analog electrical signal; the difference between two measurements of a signal (as between the input and output signal)
n. [ L. distortio: cf. F. distortion. ] 1. The act of distorting, or twisting out of natural or regular shape; a twisting or writhing motion; as, the distortions of the face or body. [ 1913 Webster ]
2. A wresting from the true meaning. Bp. Wren. [ 1913 Webster ]
3. The state of being distorted, or twisted out of shape or out of true position; crookedness; perversion. [ 1913 Webster ]
4. (Med.) An unnatural deviation of shape or position of any part of the body producing visible deformity. [ 1913 Webster ]