Something used for scratching, like a tool, or a lottery ticket where you scratch off a coating to reveal hidden numbers.
From 'scratch' (to mark a surface with something sharp) plus the agent suffix '-er' (one who does something). The lottery ticket meaning emerged in the 1970s with instant-win games.
Scratch-off lottery tickets were a gambling revolution—they made gambling instant and impulsive instead of waiting for a drawing, which is partly why they're so addictive and profitable for states. The psychology of the immediate reveal is incredibly powerful.
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