Business jet, private jet or, in slang, bizjet is a term describing a jet aircraft, usually of modest size, designed for transporting small groups of business people for commercial reasons at a time convenient to their business needs. Some business jets may be adapted for other roles, such as the evacuation of casualties or express parcel deliveries, and a few may be used by public bodies, governments or the armed forces. The more formal terms of corporate jet, executive jet, VIP transport or business jet tend to be used by the firms that build, sell, buy and charter these aircraft. The allied term "bizprop" is in use amongst enthusiasts to refer to turboprop-powered aircraft used in similar roles but seems unlikely to spread.