A DSP operation initially designed to stretch soundfiles in their duration, ideally without affecting their pitch (or pitches). This is the same proceedure that allows pitch transpositions without changes in the soundfile’s duration (pitch-shifting). When applied exaggeratedly to complex events, time-stretching abandons its initial goal of changing duration to that of creating less predictable events recalling Pierre Schaeffer’s experience in ’Les Seuils Temporels de l’Oreille’. This relates to what I call ’non-linear response’ of electroacoustic equipment. (Source - Rodolfo Caesar (1992). The Composition of Electroacoustic Music. PhD Thesis, University of East Anglia.)
See also:
FFT, Granular Synthesis and Resynthesis, Phase Vocoder, Time Compression, Time-scalingBibliography:

