I just learned this bit of legalese; here's the Black's Law Dictionary definition:
wild deed. (1914) 1. A recorded deed that does not appear to be in the chain of title because a previous conveyance in the chain of title was either not recorded or not properly indexed. 2. A deed by which a grantor purports to convey or create an interest that the grantor does not own, esp. a deed from a complete stranger to title.