What is meant by market in the lower-of-cost-or-market rule?

Stock is valued at lower of : cost or market price [prudence principle]

Explanation:

Prudence or Conservatism is an accounting principle : anticipating for all possible losses & expenditures, not anticipating for possible profits & gains. This makes business better prepared to face all contingent expenditures / losses.

This concept's implication is that : Stock or Inventory is valued at the value whichever is lesser between 'cost of inventory' & sale price. This makes inventory valuation as per the above explained Prudence / Conservatism principle.