Definitions of endorsement
an act of giving your approval or support to someone or something, especially in public; a recommendation of a product in an advertisement
The Queen's endorsement for Tesco is as near to a royal warrant as you can get.
an amendment to an insurance policy
After five years of litigation NAICO sent Rapid a letter denying coverage on the basis of an exclusion in the self-insured retention endorsement.
the action of signing a cheque, bill of exchange or other negotiable instrument to make it payable to another person or cashable by any person; the signature itself
A blank endorsement consists of nothing but a signature and allows any party in possession of the endorsed item to execute a claim.