v. 1
To make a copy of.
Can you duplicate this kind of key?
v. 2
To do repeatedly; to do again.
You don't need to duplicate my efforts.
n. 1
One that resembles or corresponds to another; an identical copy.
This is a duplicate, but a very good replica.
adj. 1
Being the same as another; identical, often having been copied from an original.
This is a duplicate entry.

Related words

Is a kind of: copy

Forms

Plural: duplicates → copies, duplications, reproductions, replications…
Past participle: duplicated
e.g. duplicated → doubled, replicated, repeated, reproduced…

Choose the right word

Duplicate or Copy?

A copy is as nearly like the original as the copyist has power to make it; a duplicate is exactly like the original; a carbon copy of a typewritten document must be a duplicate; we may have an inaccurate copy, but never an inaccurate duplicate.

J. C. Fernald, English Synonyms and Antonyms (1914)

Example sentences

repeat History does not repeat itself, but it does rhyme.
reproduce Let us try to reproduce what happened yesterday.
replicate Can Algeria replicate the Turkish economic model?
resemble The two buses resemble each other at first glance.

Popularity over time

Word	1850 → 2019	Trend
duplicate		falling
repeat		rising
reproduce		rising
replicate		rising
reduplicate		steady
resemble		steady

Use in printed books, per decade from 1850 to 2019.

By length

4 letters: same¹, copy², twin¹, dual², dupe¹
5 letters: extra², duple
6 letters: double², repeat²
7 letters: replica³, imitate³, twinned, twissel
8 letters: parallel³, matching², resemble³, manifold³, likeness²
9 letters: reproduce³, replicate³, imitation⁴, tombstone², facsimile⁴
10 letters: transcript²
11 letters: counterpart³, replication⁴, duplication⁴, reduplicate
12 letters: reproduction⁴

The small number after each word is its number of syllables (copy² = 2 syllables).

In other languages

Français: dupliquer
Español: duplicar
Deutsch: vervielfältigen