1) Coin stamped for a later year 
Shown date made by superimposing numbers on a previously dated die.
• (v. t.) To date later than the true or proper period.
A coin struck from a die with one or more digits of the date repunched over a different digit, e.g. the 1942/1 Mercury dime.
The date made by a Mint engraver superimposing one or more numbers over the date on a previously dated die.
O`ver·date' transitive verb To date later than the true or proper period. Milton. 
Shown date made by superimposing numbers on a previously dated die.
a coin stamped from a die altered to show a year subsequent to that for which it was cut.