[noun] a change for the worse Synonyms:deformation
[noun] a shape resulting from distortion Synonyms:distorted shape
[noun] an optical phenomenon resulting from the failure of a lens or mirror to produce a good image Synonyms:aberration, optical aberration
[noun] 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); "heavy metal guitar players use vacuum tube amplifiers to produce extreme distortion"