"Nongovernmental" refers to things or organizations that are not part of or controlled by the government. It means it is independent and operates separately from the government. Full definition
Ideally, an intersectoral team — including, for example, programme managers and staff responsible for nutrition and maternal and child health, academics, and national and international nongovernmental organizations — will use the tool as a basis for strengthening national policies and programmes that contribute to improved infant and young child feeding. (who.int)
He has frequently worked with the Heartland Institute, appearing on podcasts and speaking at their annual Nongovernmental International Panel on Climate Change (NIPCC) conference. (americafirstenergyconference.com)
Near Rio there was an unofficial meeting of nongovernmental organizations of many sorts. (religion-online.org)