S. Wlliam A. Gunn, MD, MS, FRCSC, FRCSI (Hon), DSc (Hon), Dr.h.c., is a Canadian surgeon and senior international health official involved in emergency disaster management and humanitarian medicine. For many years he was director of the Emergency Humanitarian Operations of the World Health Organization, where he conducted numerous field missions, advised governments and the United Nations, organized high level national programmes, lectured at universities and conducted training courses for disaster managers, services that have been recognized by Honorary Doctorates and other high distinctions. Member of many surgical, emergency and humanitarian organizations, Dr. Gunn was a founder, now President Emeritus, of the World Association for Disaster and Emergency Medicine, is the founding President of the International Association for Humanitarian Medicine, and member of the Academic Council on the United Nations System. Editor of several disaster and humanitarian journals, and author of eighteen books, he has also been head of WHO’s scientific terminology, which explains the multilingual lexicography, standard setting acknowledgement and recognized authority of the initial edition of this Dictionary.