A backer is someone who supports a plan, especially by putting money behind it. A new shop, a film, a politician, a sports team — the backer is the person or company that helps it happen, often the one who pays. It comes from the verb to back, meaning to support, the way you stand behind someone. You can have backers who only cheer, but the word most often points to money. It is a newspaper and business word; in everyday talk people also say supporter, or investor if it is only money. If the main backer pulls out, the plan may die.