We don't have synonyms for dead stock yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are dead stop, deadstock and deal stock.
(n) :
Alternative form of deadstock. [Merchandise that has not yielded any use yet: from the view of the businessperson, one that has failed to be sold or processed and is now stowed away for possible sale or manufacturing at a later date, from the view of the consumer, a piece that has been obtained but not found application and is now—perhaps even with original labelling or packaging—stored for future ideas.]
(n) :
Alternative form of deadstock. [Merchandise that has not yielded any use yet: from the view of the businessperson, one that has failed to be sold or processed and is now stowed away for possible sale or manufacturing at a later date, from the view of the consumer, a piece that has been obtained but not found application and is now—perhaps even with original labelling or packaging—stored for future ideas.]