The Collaborative International Dictionary of English v.0.48:
off-site \off-site\ adj. Taking place or located away from the specified site; as, an off-site waste treatment operation. Opposite to on-site. [WordNet 1.5]WordNet (r) 3.0 (2006):
off-site adj 1: taking place or located away from the site; "an off-site waste treatment operation" [ant: on-site]