U.S. Department of Transportation (DOT) abbreviation for Not Otherwise Specified. The same term is used in other fields as well. DOT regulations require that a Proper Shipping Name (PSN) be used when labeling shipments of hazardous materials. In many instances, these will be generic (broad classes of) names such as "poisonous liquid, n.o.s."  0 (src: http://www.ilpi.com/msdS/ref/nos.html)