Source : Webster's Revised Unabridged Dictionary (1913)

Ditto \Dit"to\, n.; pl. {Dittos}. [It., detto, ditto, fr. L.
   dictum. See {Dictum}.]
   The aforesaid thing; the same (as before). Often contracted
   to do., or to two ``turned commas'' (``), or small marks.
   Used in bills, books of account, tables of names, etc., to
   save repetition.

         A spacious table in the center, and a variety of
         smaller dittos in the corners.           --Dickens.