A public–private partnership is a long-term arrangement between a government and private sector institutions. Wikipedia

A joint venture between corporations and government or between community members and government or business beyond the course of normal interaction. OmegaWiki

An arrangement by which one or more private firms agrees to fund, create, or operate a facility, service, or other element of public infrastructure (such as a school, hospital, or highway) which is usually the sole responsibility of government, in return for all or some of the revenue generated by that facility or service. Wiktionary