A person who endorses something, such as a document, product, or idea; someone who gives support or approval.
From 'endorse' + '-er' (suffix indicating an agent who performs an action). Emerged in English as commerce created the need to identify the person signing the back of a document.
A celebrity endorser is paid to tell you a product is great, but the word originally came from bank transactions—when someone would sign the back of a check to give it to someone else.
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