Live-set refers to any performance of electronic music that is generated live out of a bank of equipment or a laptop rather than played from a pre-recorded medium (such as vinyl and CD with turntables, or mp3/wav with DJ software such as Traktor, Serato or Virtual DJ. In those cases it's DJ mix).
In some cases, advanced DJ mix can include live-set elements (e.g. Traktor's remix decks, cue juggling, live re-sampling...).
Electronic music live-sets can also include live instruments and singing.
Notable performers of live-sets
References
Live-set Wikipedia(Text) CC BY-SA