to keep adding to a large supply of goods, weapons etc that are being kept for use or possible use in the future:
• The US government began stockpiling oil in response to the oil embargo.
— stockpiler noun [countable] :
• We have yet to see one of the big stockpilers of gold announce significant disposals.
— stockpiling noun [uncountable] :
• the stockpiling of chemical and biological weapons
Financial and business terms. 2012.