The progressive reduction in amplITude of a signal as IT travels farther from the point of origin. For example, an electric signal' s amplITude reduces wITh distance due to electrical impedance. Attenuation is usually measured in decibels [per metre?]. Attenuation does not imply appreciable modification of the shape of the waveform (distortion), though as the signal amplITude falls the signal-to-noise ratio will also fall unless the channel ITself is noise free or the signal is amplified at some intermediate point(s) along the channel. ["Networking Essentials, second edITion", Microsoft Corporation, pub. Microsoft Press 1997]. (2003-07-29)