Property that belongs to no person and which may be claimed by a finder.
Also stated to be stray or unclaimed goods.
The common law in regards to "finders keepers, losers weepers" varies from jurisdiction to jurisdiction and can be tempered by statute. generally, though, a finder of a "stray" chattel left at a public place acquires title, which cedes only to a prior owner actively seeking the chattel; whereas chattel left on private property belongs to the private property owner subject again only to the prior owner actively seeking the stray and lost chattel.
Some jurisdictions have laws that suspend the finder's ownership rights until a certain period of time has passed, that the finder seek the looser, or require surrender of the property to the government during that time.
In some states, the government becomes owner of all bona vacantia property.