duplicate

Definitions

General English

Information & Library Science

  • noun an extra copy of a book or document already in stock
  • verb to make an exact copy of something

Military

  • verb to produce two copies of a document

Origin & History of “duplicate”

like its close relative double, duplicate comes ultimately from Latin duplus ‘two-fold’, a compound adjective based on Latin duo ‘two’ and an Indo-European element *pl- which denoted ‘folding’ (it is present also in English fold and ply). English acquired this in the 16th century, and its synonym duplex (based on the extended stem *plic-) in the 19th century. In Latin, duplus formed the basis of a verb duplicāre ‘make twofold, double’, from whose past participle English gets duplicate, while duplex has given us duplicity (15th c.).
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