In three copies. I need all of these forms in triplicate—can you get that together before my 3:00 meeting?
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
[of a document] produced in three copies. Mr. Smith asked me to copy his notes in triplicate. I completed each form in triplicate.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.