0 someone, especially a well-known person, who appears in an advertisement saying that they use and like a particular product:
The footballer is the company's first male celebrity endorser.
1 someone who makes a public statement saying that they support someone or something:
2 the person who signs the back of a cheque, bill of exchange, etc. written out to them in order to give permission for it to be paid to someone else:
We can complete it step by step however long the road is and it can't be completed however short the road is if you don't even mark your footprint.