+1 for dryer coin. https://www.error-ref.com/dryer-coi...is term is used,surface in the heated chamber.
A dryer coin such as this is of course a coin that remained in the clothing ( such as my Levi's pants) and falls out of the pocket and gets caught in the grove between the turning dryer basket and the support and gets compressed inward. It is similar to how coins are made into rings, so the edge becomes flanged and the lettering disappears at the rim. coin metal is "relatively " soft. Jim
It's clearly an altered/damaged Dime. It occurred after it left the Mint. Not a Mint Error of any kind. Dryer coin is correct. Here is some information - Dryer Coins (error-ref.com) BTW - Broadstruck coins would have the appearance of a larger/wider than normal size of the coin. That's bacause the 3rd collar was not in place when the Obverse and Reverse Die struck the blank planchet.