Something that cannot be sold (except for scrap value) is worthless.
Provide a different definition.
INVESTOPEDIA EXPLAINS 'Scrap Value'
For example, John has a very old car with a transmission that is shot. Because the cost to replace the transmission ($2,000) is significantly more than what the car would be worth even with a working transmission ($1,000), John decides to sell the car for its scrap value. He takes it to a junkyard where the car's usable parts and metal are valued at $500. Therefore, $500 is the car's scrap value.
Dictionary.com
to discard as useless, worthless, or ineffective
IRS again
Decline in market value of stock. You cannot deduct as a theft loss the decline in market value of stock acquired on the open market for investment if the decline is caused by disclosure of accounting fraud or other illegal misconduct by the officers or directors of the corporation that issued the stock. However, you can deduct as a capital loss the loss you sustain when you sell or exchange the stock or the stock becomes completely worthless. You report a capital loss on Schedule D (Form 1040).