1) Copy 2) Document with two copies 3) One of three copies 4) Reproduce threefold 5) To triple 
Triplicate (foaled 1941) was an American Thoroughbred racehorse. He was sired by the 1928 American Horse of the Year and U.S. Racing Hall of Fame inductee, Reigh Count. His dam was Fairday, a daughter of another Hall of Fame inductee, Fair Play. Triplicate was purchased as an unsuccessful three-year-old for $6,000 by actor/dancer Fred Astaire who ...
• (v. t.) Made thrice as much; threefold; tripled. • (n.) A third thing corresponding to two others of the same kind.
Folded three times. ... (09 Oct 1997) ... 
[n] - one of three copies 2. [v] - reproduce threefold
triplicate 1. One of a set of three identical objects or copies. 2. To make threefold; triple.
noun one of three copies; any of three things that correspond to one another exactly