Items purchased but never used and still in their original packaging. Also called new unused stock or surplus stock.
The term refers to merchandise being offered for sale which was manufactured long ago but that has never been used. Such merchandise may not be produced anymore, and the new old stock may represent the only current market source of a particular item.
Some people refer to such merchandise as new obsolete stock to further indicate that the parts have not been manufactured for several years. This describes parts or materials, that are used in obsolete equipment or the like.
Other people refer to new original stock meaning that they are original equipment parts that remained in inventory for a use that never came. Automobile dealers and parts companies often sell such slow moving stock at a discount. Other specialty parts vendors then market these NOS parts that may either decline or increase in value depending on their type and desirability.