Ditto means the same as what has already been said, the same as what has been written above, the same as what has been written before. Ditto may be a noun, the plural is dittos. Ditto may also be an adverb. As a transitive verb, which is a verb that takes an object, ditto means to make duplicates or to do again. Related words are dittos, dittoed, dittoing. Ditto comes from the Italian detto in the early 1600s, and was originally used to avoid repeating the month and year in writing a series of dates. By the 1670s, ditto came to mean the same as above or aforesaid, in written English. By the 1770s ditto came to be used as a spoken verb, meaning to express agreement with what has been said by another. Soon, ditto came to mean a duplicate or exact resemblance. Ditto machines were popular through the twentieth century, making paper copies through a mimeograph process. Ditto machines were abandoned with the advent of Xerox machines.
A ditto mark (or ditto sign) is a symbol (“) which signifies ditto, meaning the same as above or before. The plural is ditto marks.
Examples
Love re-upped with the Cavs when everyone thought he’d run back to L.A. because he wants to win a championship. Ditto for veterans Mo Williams and Richard Jefferson, free agents who chose Cleveland over other suitors. (USA Today)
It looks homemade, full of almonds and buttery with luscious chocolate topping; ditto the Walnut Layer Cake with Cream Cheese-Spice Buttercream. (The Houston Chronicle)
Same goes for floods and fires; ditto for loss of electricity or water. (The Dallas Morning News)
Some who signed the petition live outside the library district, and in some cases, ditto marks were used in address lines, Binns II wrote in the objection. (The Herald News)