This definition appears very rarely
Samples in periodicals archive:
MUN Conference The THIMUN (The Hague International Model United Nations) conference is a five-day simulation of the United Nations for secondary school students, which takes place at. read more.
Moreover, The Hague International Model United Nations, annually in January, is a five-day conference held at the World Forum, gathering over 4,000 students from over 200 secondary schools across the globe. It is the oldest and largest high school United Nations simulation in the world. Den Haag Sculptuur is an open-air exhibition of sculptures. The 10th edition, in 2007, celebrated the 400 years of the relationship between the Netherlands and Australia.
MUN in the Netherlands is almost entirely related to The Hague International Model United Nations (THIMUN) conference, which includes over 3500 participants coming from 100 different countries.  Although it is not located near the United-Nations Headquarters in New-York, it is one of the pioneer MUN conferences in the world, since it has been founded in 1968 and located in the International Court of Justice's (ICJ) world city of the Hague.