Blank endorsement of a financial instrument such as a check is only a signature, not indicating the payee. The effect of this is that it is payable only to the bearer – legally, it transforms an order instrument ("pay to the order of (the payee)") into a bearer instrument ("pay to the bearer"). It is one of the types of endorsement of a negotiable instrument.
It is "an endorsement consisting of nothing but a signature and allowing any party in possession of the endorsed item to execute a claim."[1]
A blank endorsement is commonly known and accepted in the legal and business worlds.[2][3]
This is also called an endorsement in blank[2] or blank indorsement.[4]
The prevalent spelling in American English is endorsement; the minority convention, indorsement, is found in older American documents.