WordNet (r) 3.0 (2006):

sell short
    v 1: sell securities or commodities or foreign currency that is
         not actually owned by the seller, who hopes to cover (buy
         back) the sold items at a lower price and thus to earn a
         profit
    2: underestimate the real value or ability of; "Don't sell your
       students short--they are just shy and don't show off their
       knowledge"

Moby Thesaurus II by Grady Ward, 1.0:

51 Moby Thesaurus words for "sell short":
   belittle, clear the trade, close out, convert, convert into cash,
   cut under, deprecate, depreciate, disparage, dump, effect a sale,
   job, liquidate, make a sale, make light of, make little of,
   make nothing of, market, merchandise, minimize, misestimate,
   misprize, move, resell, retail, sacrifice, sell, sell off,
   sell on consignment, sell out, sell over, sell retail, sell up,
   sell wholesale, set at naught, set little by, shrug off,
   terminate the account, think little of, think nothing of,
   turn into money, turn over, undercut, underestimate, underprize,
   underrate, underreckon, undersell, undervalue, unload, wholesale