Other forms: duplicated, duplicates, duplicating
To duplicate is to make an exact second copy. Duplicate the file, a duplicate key, in duplicate.
In duplicate means two copies of a document, one for each party, which is why forms used to be printed on carbon paper. As an adjective a duplicate is the copy rather than the original, and to duplicate effort is to waste it doing what somebody else has done.
1verbduplicateTo make an exact second copy.
“Could you duplicate this key for me so my sister can have one?”
duplicate is a copying.
Latin duplicatus comes from duplicare, to double — duo, two, plus plicare, to fold.
Proto-Indo-European
*dwóh₁
Latin
duplicō
English, today
duplicate
Borrowed from Latin duplicō. Borrowed from Latin duplicātus, perfect passive participle of duplicō, see -ate.
Etymology from Wiktionary, CC BY-SA