du·pli·cate • adj. / ˈd(y)oōpləkit/ 1. exactly like something else, esp. through having been copied: a duplicate license is issued to replace a valid license which has been lost.2. having two corresponding or identical parts: a duplicate application form. ∎  twice as large or many; doubled: duplicate taxes on oil and gas.• n. / ˈd(y)oōpləkit/ 1. one of two or more identical things: books may be disposed of if they are duplicates. ∎  a copy of an original: locksmiths can make duplicates of most keys.2. short for duplicate bridge.3. archaic a pawnbroker's ticket.• v. / ˈd(y)oōpləˌkāt/ [tr.] make or be an exact copy of: a unique scent, impossible to duplicate or forget | fig. they have not been able to duplicate his successes. ∎  (often be duplicated) make or supply copies of (a document): information sheets had to be typed and duplicated | [as adj.] (duplicating) a duplicating machine. ∎  multiply by two; double: the normal amount of DNA has been duplicated thousands of times. ∎  do (something) again unnecessarily: most of these proposals duplicated work already done.PHRASES: in duplicate consisting of two exact copies: forms to complete in duplicate.DERIVATIVES: du·pli·ca·ble / -plikəbəl/ adj.du·pli·ca·tive / -ˌkātiv/ adj.

duplicate adj. XV; sb. XVI. — L. duplicātus pp. of duplicāre, f. duplus (see prec., -ATE 2).
So vb. XV. duplication XV. — F. or L.