Definition of at a discount:
(v) :
to deduct from an account, debt, charge, and the like; to make an abatement of; as, merchants sometimes discount five or six per cent for prompt payment of bills; to lend money upon, deducting the discount or allowance for interest; as, the banks discount notes and bills of exchange
(n) :
a reduction in price; a deduction made for interest, in advancing money upon, or purchasing, a bill or note not due; payment in advance of interest upon money
(adj) :
of goods, available at
reduced prices; discounted; of a store, specializing in goods at reduced prices
"this store specializes in discount wares."