Definitions for "Relisting"
The relisting of an item occurs when it has not sold within its allotted auction time.
If your item doesn't sell the first time you list it, you can usually re-list with special pricing. Sites like eBay allow you to do this once if certain terms are met, such as your auction having recieved no bids that exceeded your reserve price or you're relisting within 30 days.
Listing an item for sale again after it did not sell the first time. If you re-list an item, and it sells the second time, eBay automatically refunds your re-listing fee (some restrictions apply).